As a result, the twin turbo technology in the BMW 335i Coupe represents a significant achievement in terms of both performance and fuel economy. The advantages over a conventional turbocharged engine are not only clearly measurable, but easy to feel on the road.

This new high-performance engine gives the light, aerodynamically sculpted Coupe outstanding acceleration and flexibility. The twin turbo powerplant in the BMW 335i Coupe develops its power and performance much more spontaneously than a turbocharged engine of conventional design.

At the same time the new engine offers all the smoothness and refinement which made BMW's award-winning inline sixes so admired. Last but certainly not least, the impressive increase in power on the twin turbo engine versus a conventional normally aspirated six-cylinder engine comes without any significant increase in fuel consumption.

Turbocharging typically includes intercooling of the engine's induction air, that is, cooling the compressed air that emerges, very much heated up by the compression process, from the turbocharger(s). Sometimes it's done with coolant; in the case of the N54 engine, it's accomplished with outside air. Intercooling is desirable, often necessary, to reduce the temperature of the incoming air to preclude detonation or "knocking" that can reduce power or, in the extreme, damage the engine. Of course, the N54, like the N52 and all other current BMW engines, is equipped with knock control. 

As effective as the magnesium/aluminum engine construction is for saving weight, the significantly increased loads and cylinder pressures of the N54 300-hp engine required the use of an aluminum engine structure with cast-iron cylinder sleeves. Of course, some, but not all, of the N52's magnesium/aluminum weight saving was lost. Altogether, the N54 weighs 419 lb.; the N52 357.

A new high-precision direct fuel injection system with piezo injectors also enhances performance and fuel efficiency. A 2nd-generation evolution of the system found on the 760's V12 engine, it is a key factor in achieving BMW's goals for this engine. The new system's main advance over its predecessor is that it provides the engineers a greater degree of freedom in the calibration of fuel quantity and timing and the distribution of the fuel-air mixture in the combustion chamber.

A piezo injector, a recent advancement in fuel injector technology, uses an actuator that takes the place of the solenoid valve in a conventional injector. The actuator, which works significantly faster than the solenoid, significantly reduces the injector's response time. That results in, according to researchers who led the piezo injector's development, a 2-3% fuel savings and 20% less emissions. 

For the first time in a 3 Series model, the 335i Coupe's dual exhaust system runs at both sides of the vehicle - logical, as each contains its own turbocharger turbine and therefore requires extra space. At low loads, a flap channels most gas through one side to reduce low-frequency exhaust "rumble." The 335i Coupe features an air-to-oil external oil cooler mounted in one wheel well as opposed to the N52's coolant-to-oil unit.

The peak power of 300 hp has already been mentioned; this is fully 45 more than the 2006 330i Sedan and 70 hp up on the new 328i Coupe. At least as important is the fact that this engine can deliver its peak torque from 1400 rpm - not far above idling - to 5000 rpm. On the road, this power and torque result in outstanding performance. The 335i Coupe with manual transmission accelerates from 0 - 60 mph in just 5.3 seconds. This sense of urgency continues all the way to the electronically limited top speed of 150 mph when equipped with the optional Sport Package.



A transmission for any driving style

As in the 3 Series Sedans and Sports Wagons, each new Coupe has as standard equipment a 6-speed manual transmission specifically tailored to its performance capability. In the 328i, it is a Getrag Type I, with the same ratios as in the 2006 325i Sedan - with relatively "short" 1st-, 2nd- and 3rd-gear ratios to enhance acceleration.

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