I've done it consistently with 4 diffferent 124/119s over a period of about 10 years, except 92s get a bit lower mileage, which is reflected in the EPA ratings. I've always been able to beat the EPA ratings, even the old ones, by 15 to 20 percent in all brands and that's all that is. I didn't know you were driving a 100 - I can see 22 mpg at 100 mph. E420 mileage isn't comparable to any other MB V8. It has a 2.24 rear axle ratio, I believe the tallest ever installed in an MB, and it's a light car at least compared to 140 bodies.