[aerohead]

There is great variability in relationships published for weight,as with respect to its influence on mpg.Published research reflects "averages" for the time in which the research was conducted and results published.------------------------------------- I would place a very high confidence in the work of Gino Sovran,with General Motors Research Labs in the 1980s.-------------------------------------------------- For an intermediate- sized car of 1279 kg (2,813-lbs),Cd 0.45,Af 1.98 m squared, a 10% reduction in weight,was good for an average 4.51% improvement in mpg.Urban mpg would see the greatest benefit.Highway mpg would see the least benefit as I'll illustrate in the following example.----------------------------------- In the early 1990s,I added 1,300-lbs(a 65 % weight increase) ( 590 kg ) to my CRX,and it only reduced highway mileage by less than 4%,dropping from 52,to 50-mpg.