The most obvious changeapart from its leaner, more dramatic stylingis a significantly revised Oilhead engine that should be considered an entirely new generation of the breed. A 2.5mm increase in stroke along with the old motor's 101mm bore brings displacement to 1170cc. Not only is the engine 8 percent more fuel efficient, it also pumps out an impressive 100 horsepower, up from the 1150's 85. It does this via new cylinder headsstill with four valves per cylinder and midmounted, chain-driven single camscoupled with a revised dual-plug system controlled by thoroughly revised engine management. In the previous two-spark engines, the plugs fired simultaneously, but the new setup can stagger ignition timing (called "phase shift") to improve driveability and fuel economy. These improvements, allied to a new solid-state knock sensor that permits the use of subpremium unleaded fuel, allowed BMW's engineers to boost the compression ratio by a full point, to 11.3:1.