Driving dynamics

The All-New BT-50 is a genuine active lifestyle vehicle with SUV-like power and handling to go wherever work, the family or hobbies demand. And better still, the BT-50 allows you to go there in passenger-car-like comfort. Driveability, design and comfort: just three of new BT-50's values.

The all-new Mazda BT-50 is intended to give superb dynamic performance that realizes an enjoyable, confidence-inspiring, environment-friendly, and economical driving experience never offered by conventional pickup trucks. The overall driving dynamics have been greatly improved and class-topping levels of performance feel, steering and handling, ride quality, braking performance, and quietness.

Major attributes of driving dynamics

To give a superior performance feel through powerful, responsive engine performance while achieving excellent fuel efficiency and low emissions, the all-new Mazda BT-50 has an entirely renewed, potent powertrain lineup consisting of 3.2-litre and 2.2 litre diesels along with 6-speed automatic and 6-speed manual transmissions.

Light, compact engines and highly efficient transmissions work together to reduce fuel consumption and carbon-dioxide (CO2) emissions for greater environmental performance. They also suppress noise and vibration for a more comfortable, quieter ride.

In developing the all-new Mazda BT-50’s chassis and body, the kind of passenger-car-like steering, handling, and ride comfort that people experience in SUVs was pursued.

The vehicle offers high driving stability even when it’s carrying cargo and a comfortable ride even when it’s empty. Its dynamics feel reassuring regardless of driving conditions. Dependable braking performance also promotes driver confidence. The all-new BT-50 is particularly notable for combining passenger-car-like ride comfort with the powertrain durability and rough-road performance that Australian utility buyers demand.

Engines

There are two newly developed common-rail, direct-injection, turbocharged diesel engines (the MZ-CD 3.2 I5 and MZ-CD 2.2 I4) which are tuned to match the BT-50's reliable pickup characteristics. These new diesel engines replace the MZR-CD 3.0 and MZR-CD 2.5 on the outgoing model. The new engines offer power and torque increases with improved fuel efficiency and lower CO2 emissions.

MZ-CD 3.2 I5

The new 3.2-litre diesel engine has an inline 5-cylinder configuration (a first for Mazda) with 20 valves, a turbocharger with an intercooler, and the latest common-rail direct injection technologies.

It has a bore of 89.9mm and a stroke of 100.7mm for a displacement of 3,196cc. It gives class-leading maximum power of 147kW at 3,000rpm and class-leading maximum torque of 470Nm at 1,750–2,500rpm (EEC). A torque curve with a flat peak from the low to the mid rev range yields superb practicality and contributes to a superior performance feel. It promotes engine response during gradual acceleration from a constant speed and helps to preclude downshifts when the vehicle starts climbing a gentle slope.

The MZ-CD 3.2 I5 has a cast-iron cylinder block, which is divided into upper and lower parts. The upper and lower parts have a ladder-frame construction for superior stiffness in the block, main bearings, and transmission mount and accordingly low noise and vibration. A lightweight aluminium cylinder head has a two-part design that enables the top half of the cylinder head to hold the camshafts.

The camshaft system is driven by a maintenance-free timing chain. Maintenance-free hydraulic lash adjusters are integrated into the rocker arms. They make valve-clearance adjustment unnecessary and help to limit noise and vibration.

The MZ-CD 3.2 I5 is Mazda’s first 5-cylinder engine. A greater displacement than that of the MZR-CD 3.0 was desired for higher power and torque, but the 4-cylinder configuration of the MZR-CD 3.0 was not appropriate; enlarging the bore or stroke of a 5-cylinder engine tends to cause NVH issues that result in the need for a balancer shaft or other measures to reduce second-order shaking forces; the engine becomes excessively big. By choosing the I5 configuration, a highly efficient, compact engine design was realized; the MZ-CD 3.2 I5’s external dimensions are only slightly greater than those of the four-cylinder MZR-CD 3.0.

The engine is longitudinally positioned closer to the vehicle's centre of gravity to minimize the inertial moment. The greater number of cylinders means shorter (but consistent) combustion intervals and accordingly limited vibration and noise. The MZ-CD 3.2 I5’s configuration is the best way to simultaneously meet the needs for excellent performance, high fuel efficiency, and a comfortable ride.

The MZ-CD 3.2 I5 has an advanced common-rail direct-injection system. A three-piston high-output fuel pump supplies fuel at an ultra-high pressure of 1,800 bar (200 bar higher than the system of the MZR-CD 3.0) through a precise multi-stage injection system with piezo injectors. An optimal cone spray angle for each injector and precisely controlled injection timing complement the high injection pressure to realize optimal combustion throughout the combustion chambers so the system achieves better fuel economy without detracting from power. The result is a combination of high power, low fuel consumption, low emissions, and quiet operation.

The engine has an oil-cooled variable-nozzle turbocharger (VNT) in which electronically adjusted guide-vane geometry optimizes the speed and volume of the exhaust gases that strike the turbine blades, thereby suppressing turbo lag and enabling torquey performance throughout the rev range. The intercooler has greater cooling capacity than that of the MZR-CD 3.0 owing to bigger dimensions (670mm height, 213.9mm width, and 38mm depth versus the current 250mmheight, 206mm width, and 65mm depth).

The intake system is made of plastic, which has the merits of lightness and formability into complex shapes. It’s optimally tuned to ensure that the same amounts of air and recirculated exhaust gases go into each cylinder for low emissions.

A shutoff shake reduction system in the intake system significantly reduces the shake usually associated with diesel engines when they’re shut down; it electronically closes the throttle at the moment the driver turns off the ignition switch, thereby softening the rate at which the engine shuts down.

The exhaust gas recirculation (EGR) system has a high-efficiency EGR cooler that further lowers the temperature of combustion and thereby suppresses nitrogen-oxide (NOx) emissions. The system is compact and has highly efficient internal components.

A powerful DC-motor-actuated valve on the cold side of the cooler controls EGR operation for optimal performance.

To promote fuel efficiency, the vacuum pump is camshaft-driven. It’s less prone to oil leaks than conventional front-end-accessory-driven devices, and its lower rotation speed contributes to higher engine durability. The camshaft-driven vacuum pump also eliminates the need for an external oil feed for lubrication. Also, a variable-flow oil pump has feedback control, which enables it to supply the required amount of oil only when the engine needs it. Relatively low power requirements for the oil pump mean low mechanical losses and accordingly good fuel efficiency.

A deep-draw oil sump allows an oil pickup location in the centre for reliable off-road performance. An oil drain plug on the right-hand side enables easy user access. Oil vapour that builds up inside the engine is separated out and returned to the sump by a crankcase ventilation system that has an oil separation function.

Engine noise and vibration are suppressed by a steel front cover, by mass dampers on high-pressure fuel pipes, by tuned ribs in the sump, and by insulation around the injectors. Even the fuel-injection timing is tuned to minimize noise.

For the durability needed for reliable performance, the materials and coatings in the fuel supply system are strong enough to withstand fuel additives used in any part of the world. Also, the alternator is mounted high for good water-wading performance.

MZ-CD 2.2

The new 2.2-litre common-rail direct-injection diesel engine has the same basic structure and fuel-supply system as the MZ-CD 3.2 I5 but has four cylinders. The cylinders each have a bore of 86.0mm and a stroke of 94.6mm for a displacement of 2,198cc. The engine is lighter and more compact than the MZR-CD 2.5 that it replaces and gives better performance.

The MZ-CD 2.2 delivers maximum power of 110kW at 3,700rpm and maximum torque of 375Nm at 1,500–2,500rpm. It features latest-generation common-rail injection technologies including the 1,800 bar ultra-high-pressure fuel system, which is tuned to suit the four-cylinder engine characteristics. It also features an oil-cooled Variable Nozzle Turbocharger (VNT) similar to that in the MZ-CD 3.2 I5.

The intercooler of the MZ-CD 2.2 has greater dimensions than that of the outgoing MZ-CD 2.5 (670mm width, 196.7mm height, and 38mm depth versus the current 200mm width, 145.3mm height, and 64mm depth).

The MZ-CD 2.2 combines outstanding power and torque with powerful towing capability, excellent fuel economy, and low emissions.

Transmissions

The all-new Mazda BT-50 is offered with a six-speed manual transmission or six-speed electronically controlled automatic transmission (model dependant).

Both these transmissions are new and fully exploit the performance of the newly developed diesel engines, promote fuel efficiency, and give a sporty, passenger-car-type shift feel that adds Zoom-Zoom driving pleasure.

6-Speed Automatic Transmission

The new 6-speed automatic transmission replaces the current five-speed automatic transmission and is available on certain models specified with the MZ-CD 3.2 I5 engine.

Closely spaced gear ratios with a wide spread give excellent torque from low engine speeds while helping to realize low emissions and improved fuel efficiency. The transmission has its own control unit, which allows high-speed gearshift control while communicating with the engine control module to enable smooth, precise shifting and excellent response to the driver’s demands.

It also features advanced shift-control technologies that have been adopted in Mazda passenger cars such as the Mazda6. These technologies include Active Adaptive Shift (AAS), which optimizes gearshift control in accordance with the driver's intentions, which it infers from multiple data and from driving conditions.

The AAS uses variables such as acceleration and deceleration rates, brake and throttle use, and cornering speeds to ensure that the vehicle is always in the right gear at the right time without undesired gearshifts. It greatly improves the vehicle’s driveability and performance feel, thereby supporting the driver in a linear, dynamic manner. On downhill roads, the AAS automatically downshifts to generate additional braking from the powertrain when it senses that the driver is applying the brakes. It thereby promotes downhill safety.

The 6-speed automatic transmission also has Sequential Shift Control (SSC), which offers Normal and Performance modes plus a Manual mode that allows sequential manual shifting. The Performance mode gives more responsive acceleration. In the Manual mode, the driver can select gears as with a manual transmission.

The torque converter has hydraulic slip lockup control, which is optimized for refinement and fuel efficiency. Extensive use of full and partial torque converter lockup also contributes to fuel economy while promoting shift response.

6-Speed Manual Transmission

The new 6-speed manual transmission has a short, car-type shift lever that’s optimally positioned for the driver, so it offers crisp, precise shifting that’s well matched to the generous torque of the new diesel engines. It’s paired with both the MZ-CD 3.2 I5 and MZ-CD 2.2. engines.

Rigid laser-welded synchronizers accommodate the exceptional engine torque while ensuring smooth shift operation with a light lever action. The first and second gears have triple-cone synchronizers. The third and fourth gears have double-cone synchronizers. The fifth and sixth gears have monocone synchronizers (not laserwelded but spline-fitted). And the reverse gear has a laser-welded monocone synchronizer. Each synchronizer is specified to optimize the transmission’s shifting characteristics.

The transmission has a link-type shifter with a decoupling device between the main and selector rails. This configuration enables a shorter shift lever and shift stroke than those of the current manual transmission and those in some competing vehicles. The result is a sportier, more passenger-car-type shift feel. An upshift indicator in the tachometer promotes fuel economy by helping the driver avoid using unnecessarily high engine speeds. A reverse inhibition function prevents the shift lever from being moved to the reverse position unless a collar on the shift knob is pulled up. Strong internal components such as hard-machined gears ensure durability.

Fuel Economy

The new powertrain technologies not only give plenty of power and torque; they also give superior fuel efficiency, which translates into economical running with a small environmental impact.

Also, the capacity of the fuel tank (made of tough, lightweight plastic) has been increased to 80 litres with all body types regardless of drive system. The combination of superior fuel efficiency and a greater tank capacity means a longer driving range between fill-ups.

Four-Wheel Drive (4WD) system

All three body types of the new Mazda BT-50 are available with a 4WD system for greater rough-road mobility. Every 4WD Mazda BT-50 (regardless of whether its transmission is automatic or manual) has an electronically controlled, shift-on-the-fly transfer case that allows the driver to shift between 2WD and 4WD at any time using a switch conveniently located on the floor console. Low-range gearing is available for extra torque or downhill braking.

The driver can choose from three driving modes: 2H (2WD high range) for all normal-road driving and for off-road driving on dry, level terrain; 4H (4WD high range) for off-road driving; and 4L (4WD low range) for more extreme off-road conditions such as steep ascents and descents, for low-speed manoeuvering, and for standing starts when the vehicle is heavily loaded or towing.

The driver can shift between 2H and 4H with the vehicle moving at speeds up to 120km/h and the accelerator pedal released. For shifting between 4H and 4L, the driver must stop the vehicle and press the clutch pedal (with a manual transmission) or place the shift lever in the neutral position (with an automatic transmission).

Electric locking rear differential

An electric locking rear differential is standard on all 4x4 versions. It maximizes off-road grip by locking both rear wheels so they both receive the same amount of torque, even when one has lost traction. The locking rear differential thereby promotes off-road running stability and helps the driver extricate the vehicle when it’s stuck in soft ground. The driver activates and deactivates the locking rear differential using an easy-to-reach switch on the centre console.

For rough-terrain driveability, the new BT-50 has high ground clearance and ample approach, departure, and breakover angles. Unladen and shod with 265 tyres, the Dual Cab XTR has ground clearance of 237mm, an approach angle of 28.2°, a departure angle of 26.4°, and a breakover angle of 25.0°.

The new BT-50 has outstanding water-wading performance thanks partly to the high-mount alternator. The maximum wading depth is 600mm for 2WD vehicles (up from the current 450mm) and a class-leading 800mm for 4WD vehicles (up from the current 750mm).

Steering, Handling, and Ride

The new BT-50 steers and handles like an SUV rather than a truck, and it offers ride comfort that’s satisfactory even when it’s used as a passenger car.

The first target was the kind of Zoom-Zoom steering and handling that are unique to Mazda, so the suspension, steering, and frame were all refined with a focus on achieving a linear steering feel. As a result, the new BT-50 gives a precise steering feel that’s characterized by smooth, linear response to even the smallest steering inputs during straight-line driving.

With regard to ride comfort, the new BT-50 gives a smooth, non-bouncy ride even when it’s driven unladen on rough roads and gives a sure-footed, stable ride when it’s carrying heavy cargo. We focused on improving rear-seat ride quality, which tends to be greatly influenced by the presence or absence of cargo. Consequently, occupants enjoy a smooth ride whether they sit in the front or in the back.

Suspension

The all-new BT-50 has newly developed double-wishbone suspension at the front. Coil springs give more linear response than the current BT-50’s torsion-bar spring.

The stabilizer control link is attached to the axle rather than to the lower arms (as it is on the outgoing BT-50); a higher lever ratio makes the stabilizer more effective for better roll stiffness. Newly optimized front-suspension geometry suppresses disturbances from the road surface. And the lower-arm bushings are made of high-damping rubber, which limits steering shimmy and promotes ride comfort.

The rear suspension has the same configuration as that of the current BT-50 (rigid axle with leaf springs) but incorporates enhancements for superior steering and handling and excellent ride comfort.

For better steering response, leaf-spring hardpoints such as the shackle mountings and leaf-eye bushings were optimized to achieve optimal roll behaviour with respect to steering inputs.

The rigidity of the shackle modules were increased for optimal compliance steering; whereas the shackles are attached to brackets on the bottom of the frame on the current BT-50, a support structure was adopted in which the upper pins pass through the frame. With the new configuration, the frame’s torsional rigidity can be used effectively as support stiffness for the shackles.

The thickness of the shackle plates has also been increased for greater rigidity in the entire shackle units.

The leaf springs on the new BT-50 are 1,330mm long (10mm longer than those on the outgoing BT-50). The extra length promotes ride comfort. Also, the leaf-eye bushings at the front have a diameter of 55mm (15mm bigger than those on the outgoing model).

Steering

Whereas the current BT-50 has ball-and-nut steering, the new BT-50 has rack-and pinion steering (the type of steering widely used on passenger cars). The rack-and pinion mechanism is highly rigid, works more precisely, and gives better road feel. Its advantages were heightened even further by using a rigid mounting structure without rubber bushings for the gearbox. The rigid mounting structure makes the steering feel even more direct.

Also, the steering-gear ratio is quicker than that of the current BT-50 (changed from 19.6 to 16.3 for 2WD vehicles and from 21.0 to 16.7 for 4WD vehicles and 2WD Hi-Rider vehicles), so it makes the steering feel lighter and the vehicle easier to manoeuvre.

Although the new BT-50 has longer wheelbases than its predecessor (235mm longer with 2WD vehicles and 220mm longer with 4WD vehicles), increased maximum steering angles yield smaller turning circles (11.8m with 2WD vehicles and 12.4m with 4WD vehicles and 2WD Hi-Rider vehicles).

Newly fitted damper valves on the steering gearbox suppress disturbances from the road, thereby enabling a smooth steering feel. Newly optimized power-assistance characteristics contribute to a more linear steering feel.

Frame

The sturdy ladder frame-type of the current BT-50 has been adopted with a number of rigidity improvements for greater nimbleness and ride comfort. The closed-section side rails were made taller, wider, and straighter.

Consequently, the frame has near-class-topping levels of rigidity (about 2.6 times the flexural rigidity and about 2.1 times the torsional rigidity of the current BT-50’s frame). We also ensured high rigidity in the frame areas on which parts are mounted, thereby realizing linear vehicle behaviour and superior quietness.

Cab mounts

The cab mounts that join the cabin to the frame suppress the transmission of vertical, longitudinal, and lateral oscillation to the cabin. The front mounts are solid rubber like those of the outgoing BT-50.

The left- and right-hand mounts under the pillars at the back of the cabin are newly liquid-filled. Resonance caused by the repetitive movement of the liquid damps low-frequency vibration, thereby suppressing shake for a more comfortable ride.

There’s no resonance at other frequencies, so it was possible to lower the dynamic spring constant at 100Hz and higher (the frequency range relevant to booming noise and other kinds of noise).

Since the damping force and dynamic spring constant were able to be tuned separately, the ride comfort and NVH suppression were able to be simultaneously improved.

Braking

Like the outgoing BT-50, the new BT-50 has ventilated disc brakes at the front and drum brakes at the rear. Improvements in brake response and linearity realize braking performance that inspires the confidence essential for an enjoyable driving experience.

The diameter of the front brake discs has been increased from 14 inches to 16 inches on all vehicles for greater heat capacity. And the single-piston calipers on 2WD vehicles have been replaced with the twin-piston calipers that feature on all 4WD models. The result is significantly better brake performance.

A highly responsive pedal feel has been achieved by means of boost characteristics that optimally match the pedal ratio.

NVH Reduction

Comprehensive steps were taken to suppress NVH in order to achieve the kind of quiet, comfortable driving experience that’s experienced in passenger cars. To limit vibration and noise while the engine is idling, increased rigidity in the frame was supplemented with increased rigidity in the framework of the cabin and softened the engine mounts and transmission mounts.

Since vibration inputs to the cabin are accordingly reduced, noise in the cabin by the driver’s window is down from 55.1dBA in the current BT-50 to 49.6dBA in the new BT-50. The average level in competing models is a noisier 52.0dBA. Vibration in the seat mounts and vibration in the steering wheel are both about half of what they are in the outgoing BT-50.

To reduce booming noise and road noise, the rigidity of the brackets and members that join the cabin to the frame was increased. The higher rigidity works with the softer engine and transmission mounts to limit transmission of noise and vibration to the cabin while the vehicle is moving.

Also, an increased diameter and softer materials for the leaf-eye bushings in the rear suspension limit transmission of resonance in the powertrain to the cabin via the rear suspension (a problem to which vehicles with leaf springs are prone). Booming noise is as low as (or lower than) that in the outgoing BT-50 at any engine speed. Damping material on the floor and other parts of the body shell cuts noise even further.

To keep sound that radiates from the engine and tyres out of the cabin, seals on the body, doors, and fenders were improved. Notably, double door seals were adopted. To sound-insulate the engine, an engine-top cover was adopted on XTR and GT models.

And to keep wind noise and the tyres’ pattern noise out of the cabin, the pillars have been filled with sound-insulating foam (a technique widely used with passenger cars).

Aerodynamics

A vehicle’s aerodynamic performance influences its high-speed driving stability and fuel economy and its interior noise. We strove to combine superior aerodynamic performance with the new BT-50’s fresh, striking looks.

To manage the vehicle’s underfloor airflow for low drag and accordingly high fuel efficiency, a chin spoiler has been adopted. The chin spoiler lowers drag by 3.5%. It also cuts front lift by 50%, so it improves the vehicle’s overall lift balance and its driving stability.

The airflow behind the cabin also affects drag. Through collaboration with the design studio and manufacturing teams, the shape of the rear pillars and the geometry of the rear combination lamps with each body type was optimized.

Drag and wind noise was reduced further by integrating the mirror sails into the A-pillars. Early in the vehicle programme, a computational-fluid-dynamics model was developed and it was used to study combinations of A-pillars and mirror sails. The results facilitated great design freedom and engineering efficiency.