Forget the sweeping curves, challenging proportions and gromless, face; what matters about the Mercedes Benz F700 is the tech. it previews tomorrows S class. First up, pre scan suspension, which uses pulsed laser to read the road upto 7m in front of the car, detecting the bumps and feeding the information to the F700’s hydraulic active body control suspension. As a bump approaches, ABC raises the body slightly, and then releases hydraulic pressure to allow free wheel movement. Ridges in the road surface are erased, for a calmer, quieter ride. Works well over speed bumps. The F700 is powered by Mercedes’ DiesOtto engine, a 1.8 liter in line four that combines element of diesel and petrol (Ottocycle) engines in the search for the cleaner, more efficient combustion. It runs on petrol, but the ignition is achieved without a spark by a controlled rise in cylinder temperature. That calls for variable value timing, a variable compression ratio, two stage turbo charging, expensive pressure sensors and sophisticated engine management to make it work and even then, DiesOtto has to switch back to spark ignition for cold starts and full throttle acceleration. Managing the transaction between the two modes is the tricky bit, but you hardly notice it when it happens.
There’s 238bhp on tap, while an electric motor adds another 20hp and boots total torque to 295lbft. Performance is brisk and fuel efficiency remarkable: fitted with a start/stop function and regenerative braking, F700 can return 53mpg. But by excellent class standard the engine is unrefined, and the technology it requires is prohibitively expensive. Some of it will pop up in Mercedes over the next few years-but don’t hold you breath.