Best Concept Car Since The "Range Stormer"

With twin sequential turbochargers & a capacity of just 1.8 litres, the F700 DiesOtto generates 238hp. An electric motor adds another 20hp & boosts total torque to 295lb ft. As a result, the S-class-sized F700 has S350 performance. Thanks to the efficiency of the engine, plus an urban start/stop function & regenerative braking, it returns up to 53mpg. Highly impressive for a big limo like this. And Pre-Scan, what’s that about? Pulsed laser sensors scan the road surface up to 7m in front of the car, detecting bumps & feeding the information back to the F700’s Active Body Control suspension. As a bump approaches, ABC uses its hydraulics to raise the body slightly, then releases the hydraulic pressure to allow free wheel movement. In effect, it lengthens & softens the springs as a bump approaches, to provide what Mercedes likes to call a ‘flying carpet’ ride. Does it really ride like a flying carpet? Mostly, yes. Roll & pitch are all but eliminated, transverse ridges in the road surface are magically erased, & minor ripples are smoothed for a calmer, quieter ride. Speed bumps are more heard than felt: Mercedes says production versions of the system will need ‘environment detection’ so the car will know when it’s in an urban area, & won’t let you race over speed bumps … & does a 1.8-litre four-pot really work in a luxury saloon? That was one of the questions Mercedes aimed to answer by building DiesOtto as a four-cylinder engine: small, light fours are bound to be more environmentally friendly that hefty multi-cylinder motors, but can they provide the performance & refinement an S-class customer expects? Performance isn’t in doubt. At 1700kg, the F700 is no featherweight (though it is light for a full-size saloon) yet the combination of 1.8-litre DiesOtto engine & the electric motor deliver brisk performance. In some ways the engine is remarkably refined: the trickiest part of getting DiesOtto to work is to manage the transition between HCCI & spark-ignition modes, which Mercedes has done incredibly well. An almost imperceptible difference in engine note is the only indication, but ultimately this is still a four-cylinder engine: it needs to be smoother & quieter for a big, pampering luxury car.