Originally Posted by Motown

... Assume that a regular Escalade might average 15 MPG (66.7 gal/1000 mi) and assume that the hybrid version gets 20 MPG (50 gal/1000 mi). To put a 16.7 gallon gasoline drop per 1000 miles in perspective, consider that to save this much gasoline by trading in a vehicle that gets 25 MPG (30.3 gal/1000 mi), you would have to get a vehicle that averages 42 MPG (23.8 gal/1000 mi).

If I were marketing cars, I would have a table in every dealership showing how much gas you would save by swapping out your current vehicle for the new one. The nonlinear gas savings is heavily weighted in favor of getting rid of inefficient vehicles that get gas mileage in the 10-20 MPG range than moving from a high MPG vehicle to a very high MPG vehicle. To cite the Escalade comparison a different way. Going from 15 MPG (66.7 gal/1000 mi) to 20 MPG (50 gal/1000 mi) saves as much gasoline as swapping two 30 MPG (33.3 gal/1000 mi) cars for two 40 MPG (25 gal/1000 mi) cars.