Two Technologies Made One
It's called DuoTec in the literature, but the engineering brass referred to the prototype as "DiesOtto," reflecting the combination of technologies that were applied to a conventional "Otto cycle" engine (suck, squeeze, bang, blow) in order to achieve the fuel economy of a diesel engine, the emissions of a super-clean gas engine and the power to satisfy even the lead-footed.
And while the prototype is a smallish four-cylinder that displaces just 1.8 liters, it's not just for some lightweight econocar. Instead, Mercedes is showing DuoTec for the first time in an S-Class sedan, underlining the point that cylinder count will cease to be a measure of performance and fuel efficiency.
As it sits in the S-Class, the new engine puts out 134 horsepower and an impressive 160 pound-feet of torque — per liter. That's a total of 241 ponies and an impressive 288 lb-ft packed into an engine the size of a Honda Civic's. This small engine is capable, Mercedes executives say, of propelling the big sedan from zero to 60 mph in 7.5 seconds while delivering fuel efficiency of around 40 miles per gallon.
The DuoTec engine runs on conventional gasoline and will be less expensive to build than a diesel — which requires costly combustion after-treatments — and, most important to the guys trying to sell it, will deliver the range and power demanded by most car buyers.
DuoTec is still five to seven years from series production, but it will likely beat the fuel cell to the retail market. When it does appear, it could have a more immediate and much larger impact than alternative fuels on both fuel economy and emissions levels.