Car Trends Magazine

The third generation of compact coupé marks the introduction of the first ever twin-turbo petrol-powered engine in a production BMW as well as pioneering Direct Injection technology. Two models will be available at launch. See more pictures cartrendsmag.blogspot.com/2...

Designed for sporting elegance
Despite its close technical ties with the 3 Series Saloon and Touring variants, designers set out with the goal of differentiating the two-door model more than its predecessors. From the front, side and rear, the car is clearly related to other 3 Series models but has its own, classically elongated, shape. Adopting BMW’s typical Coupé proportions of long wheelbase, short overhangs, long bonnet, cabin set to the rear and a low, sleek roofline, the new 3 Series Coupé has an elegant profile.

Key highlights in exterior design are the kidney grilles and restyled headlamps that give a bold yet elegant frontal view. At the rear, the broad rear lights use horizontal light rods with bright LED illumination to accentuate the low, wide appearance of the rear of the car.

Another change from the other models in the 3 Series range is the use of lightweight materials in the body construction in the Coupé. While all 3 Series models use Tailored Blanks that increase panel thickness where structural rigidity is needed, and reduces thickness where it’s not, the Coupé variant also uses plastics in construction As a result of the lightweight plastic front wings used on the 3 Series Coupé the new car is an average 10kgs lighter than the Saloon variant.

Twin-turbo in-line six-cylinder
The all-new Coupé bodyshell clothes the twin-turbo 3.0-litre engine in the new BMW 335i SE that develops 306hp and 400Nm of torque between 1,300 - 5,000rpm. With such performance statistics, the 335i forms the pinnacle of the new 3 Series range.

The 335i SE Coupé accelerates from zero to 62mph in 5.5 seconds, and, if left unchecked, would travel on to an electronically-limited top speed of 155mph. This level of performance is made possible by two turbochargers, each supplying compressed air to three cylinders each. The use of two smaller units ensures that the turbochargers react more quickly to changes in the throttle position all the way to the 7,000rpm red line while also eliminating the previous scourge of turbocharged engines – ‘turbo lag’.

The turbocharged engine is also considerably lighter than a normally aspirated powerplant of equal power. In the case of the 335i, the new twin-turbo six-cylinder engine weighs approximately 70kgs less than an eight-cylinder engine of corresponding performance. This weight advantage benefits both fuel economy and weight distribution.

BMW’s all new high-precision Direct Injection system also aids these high levels of performance while also benefiting economy. Piezo injectors, located centrally in the combustion chamber between the inlet and exhaust valves, deliver atomised fuel in a conical burst into the chamber to ensure a smooth, efficient burn.

Piezo crystal injectors work when an electrical current is passed through the crystal to create a very precise and consistent fuel delivery. The result? Only the exact volume of fuel required is delivered into the combustion chamber on each cycle guaranteeing that all the vapourised mixture is burnt. This method of injection also serves to aid combustion chamber cooling, thus offering a higher compression ratio. As aconsequence, the new car delivers an average fuel consumption of 29.7mpg on the combined cycle.

Entry-level six-cylinder
At the launch in September, the new 325i SE Coupé will form the entry point to the range. Delivering 218hp and 250Nm of torque from its 2.5-litre in-line six-cylinder engine, zero to 62mph is achieved in 6.9 seconds and the top speed is 153mph. However, performance does not compromise economy with the 325i SE Coupé delivering 33.6mpg on the combined cycle. This is made possible thanks to BMW’s patented VALVETRONIC variable induction technology and VANOS variable valve timing that, when combined, balance the requirements of performance and economy.

This level of economy is also made possible as a result of a number of weight and power saving measures in the engine. The 325i Coupé is the latest BMW to benefit from the magnesium – aluminium composite cylinder block first seen on the BMW 630i in Spring 2004. The lightweight combination of materials reduces the overall mass of the car and helps achieve the near-perfect 50:50 front-to-rear weight distribution for improved handling.

Finally, the 2.5-litre engine uses an electrically-powered water pump. This not only eliminates the engine power normally needed to drive a conventional crankshaft driven unit but also reduces the engine heat-up time to improve engine efficiency and occupant comfort.

Gearbox options
All new BMW 3 Series Coupé models come with a close ratio six-speed manual gearbox as standard. Those drivers who prefer the convenience of an automatic transmission, but the driver involvement of a manual, should opt for BMW’s new automatic gearbox option. Using an innovative torque converter and software set up, the new automatic gearbox offers a 40 per cent improvement in the response time to throttle inputs and a gear-shift time nearly half that of a conventional automatic transmission. Whenever a driver wants to take control of gear changes a pair of selection paddles located behind the steering wheel can be used to change gears

Practical and ergonomic interior
Internally, all controls fall easily and ergonomically to hand. The seatbelt is now also delivered to the driver courtesy of a feeder arm integrated into the B-pillar. This only operates on the passenger side when the airbag’s seat detector recognises an occupant.

Both driver and passenger in the 3 Series Coupé sit comparatively lower in the car than they do in its Saloon counterpart. This ensures the maximum headroom for occupants, even with the lower roofline of the Coupé, and also gives occupants a safe, cosseted feeling in the car. Practicality is also a priority with the new 3 Series Coupé offering up to 440 litres of boot space in conjunction with convenient storage solutions in the interior.

Chassis and body – a sound basis
In common with all BMW models, the new 3 Series Coupé benefits from a near-perfect 50:50 front to rear weight distribution and rear-wheel-drive for the optimum in driving dynamics. A double-joint tie bar front axle with spring struts made almost entirely from aluminium and a five-link rear axle work in combination with a rigid body structure to provide very high levels of stability and comfort.

The 3 Series Coupé also comes as standard with Dynamic Stability Control +, BMW’s latest traction control system. With DSC+, the highest levels of traction and stability are complemented by the latest comfort and safety systems including brake pads that are dried in wet weather conditions and brakes that are applied harder when any possible brake fade is detected. This ensures the car remains under maximum control at all times.

To enhance the chassis and suspension set up, the 3 Series Coupé comes with a rack and pinion steering system as standard. Customers can also opt for BMW’s innovative Active Steering system that varies the steering ratio as a proportion of road speed. The Active Steering system additionally links into the DSC+ system, adding small amounts of steering correction without driver input when oversteer is detected.

Extensive safety systems
All of the passive safety systems of the new Coupé are controlled by a restraint and support system. The six standard air bags, seatbelt pre-tensioners and belt force limiters are all activated by the type and severity of a collision.

Recognising that the majority of accidents occur in the dark, the new 3 Series Coupé comes with Xenon headlights as standard. Customers wanting to improve visibility yet further can specify BMW’s Adaptive Headlights that, using the steering angle, aim in the direction the car is travelling rather than the direction it is pointing.

Drivers following a 3 Series Coupé might also notice BMW’s Brake Force Display at work. When the driver of the Coupé needs to execute an emergency stop, or when the ABS system is in operation, the driver behind is warned of the danger ahead by an additional illumination of the LED brake lights in the lamp cluster.

Future Coupé models
Other engine derivatives start production in September to broaden the 3 Series Coupé range. The new BMW 330i Coupé will develop 272hp from its normally-aspirated 3.0-litre six cylinder engine that, like the smaller engined 325i Coupé, uses magnesium alloy in its engine construction. Acceleration to 62mph is dispatched from standstill in 6.1 seconds with an electronically limited top speed of 155mph. The 330i Coupé still delivers 32.1mpg on the combined cycle.

At the same time as the 330i, the new BMW 330d Coupé will start production, offering 231hp and 500Nm of torque. Performance and economy are both top priorities for the diesel-powered Coupé, with the car posting a zero to 62mph time of 6.6 seconds while still delivering 43.5mpg on the combined cycle. Details of the future entry-point BMW 320i and 320d Coupé models will be announced at a later date.

See the 2007 BMW 335i Video