I have a 1999 Chevy Tracker with 4WD. The 4WD is seldom used - only in slick conditions. In my normal driving, 80% up and down I25 in Colorado, I get 25-26 mpg. I will soon want to replace this vehicle but I’m confused by the rated mpg given for new 4WD vehicles. When not in 4WD can I assume that the rated 2WD mpg is appropriate, or is there such a fundamental difference that just having 4WD available is enough to enact the 4-5 mpg penalty?
Having 4wd, awd, or 4x4 always means extra weight. In 2wd you’re still pushing around that extra weight and therefore the lesser mpg that is equivilant to hauling weight in any 2x vehicle.
There will always be some kind of penalty, but for those that actually do lock out 4WD the difference will be small.
Note: The current year mileage ratings are closer to real life number than in prior years, so while a new vehicle may be rated the same or a little lower than what you have, it likely will do better than what you have.
I think you’re mixing up EPA estimates, old vs. new system. Where did you see a ‘4-5 mpg penalty’? Typically it’s about 1, maybe 2 mpg, because of the added weight and friction involved, even when in 2WD.
If I understand the question correctly, you’re asking what the EPA uses for their ratings?
As the other posters mentioned, the extra weight associated with hauling around the 4wd equipment is a factor, but also on many trucks the 4wd and 2wd versions are drastically different in other ways too. Often times, the 4wd version will ride a lot higher off the ground, have beefier suspension components, a sturdier frame will and be geared a bit lower as well.
It’d be difficult to work out an MPG rating for while you’re in 4wd because sort of by definition if you’re using it you’re in nasty conditions that are hard to quantify.