Answer depends on weight & aerodynamics! (And to a certain extent the environment you drive in.)
The previous generation Smart Fortwo CDI (Canadian / Euro market) has 40 horsepower - and a worse (from the conventional perspective) power to weight ratio than a Geo Metro 3 cylinder car. I'd drive one!
Somewhat related thread:
http://ecomodder.com/forum/showthrea...good-5285.html
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