"It only takes about 6 hp to keep an average car at 55 mph." 6hp = 4.5 kw. In one hour, your car will go 55 miles. Your car consumes 4500/55 = 81 watts/mile."
Watts is a unit of power. The car would consume (or transform) energy, not power. So, in one hour, this hypothetical car traveling 55mph might consume 4.5 Kwh, or 81 watt-hours/mile.
212 posted on 09/13/2007 10:19:01 AM PDT by Post Toasties
(It's not a smear if it's true.)