The fuel economy requirements aren’t very strict:
“For passenger automobiles, the new vehicle must have a combined fuel economy value of at least 22 miles per gallon. For category 1 trucks, the new vehicle must have a combined fuel economy value of at least 18 miles per gallon. For category 2 trucks, the new vehicle must have a combined fuel economy value of at least 15 miles per gallon. Category 3 trucks have no minimum fuel economy requirement; however, there are special requirements that apply to the purchase of category 3 vehicles.”
The best combined mileage for a new car now available in the US, according to the Govt. site, is 46 mpg (prius), 42 (Civic Hybrid), 40 (Jetta Diesel), 36 (Smart Car), 32 (Toyota Yaris), and down from there.
In 1986 (adjusted to the new measurements):Â 48 (Chevy Sprint ER), 46 (Honda CRX HF), 36 (Chevette Diesel), 33 (Plymouth Colt) and so on.
Lost ground over the past twenty years.
I don’t think it makes sense to give rebates for cars getting less than, say 30 MPG.