The big, old, and slow SUVs of years past are, well… in the past. From a willingness to suffer poor gas mileage for the sake of power and size to recognition as some of the top performers all around, we’ve come a long way since the SUV class rose to popularity. Between 1975 and 1985, average fuel economy for light trucks increased from 11.6 to 19.5 miles per gallon. Nowadays, we scoff at 19.5: modern SUVs…