Quote:
Originally Posted by ProDigit
It all depends on the load.
A 2CV with twin boxer engine supposedly got twice the mpg of current econo-cars (80mpg vs 40mpg on modern economy cars), all thanks to it's 350-500cc twin cylinder equipped with a large overdrive. The thing could only do 45mph..
Turbo engines have a very narrow rpm range where they are functional.
NA engines are more fuel efficient, especially with direct injection. A 1 liter engine usually is geared to work well in city traffic of 35mph, but are less efficient than a larger engine at higher speeds (say, a constant 60 mph)
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I just checked a test of our local car mag from year 1970. Citroen 2 CV had a fuel consumption of 33 mpg @ constant 62 mph and 50 mpg @ constant 31 mph. This tiny death capsule consumes 20-35 percent more fuel than a new VW Golf 1.0 TSI.
I really don't understand what do you mean when you say, that turbo engines have a narrow functional RPM range. They deliver plenty of useful torque on very wide rpm range. These modern 3 cylinder engines with turbo are also more fuel efficient in low and high speeds than any other engines except some hybrids. I'm just reading a test where VW Golf 1.0 TSI costumed 33.3 mpg @ constant 72 mph. Not bad for a compact car which never are too aerodynamic.