My experience with our 2016 S550e has been very different. We do a lot of short mileage trips, and often stay on pure electric the entire day. After 6000 miles, we average 34-36 mpg. High of 42. This car weight about 100 pounds less than the GLE, and is more streamline, so high speed mileage might be better, plus the 4WD might take up some as well. But I wouldn't think it would by that different. We do "baby" it to see how high we get the mileage. Obviously the more you stay on complete electric, the better it is. I have a pair of higher power chargers in the garage, one for the S, which charges it in about 1.25 hours, and one for the GLE550e which is still sitting in Alabama waiting for the update mileage window sticker since 7/29/16 when it was completed. Some of the best driving impression with the S550e is putting it in the next position below "hybrid", I think called "e mode". You can depress the peddle much further than on "hybrid" without the engine coming on, and accelerate rather quickly, at least for city driving. It's good up to about 80 MPH. But it's really for short trips like 14-15 miles, which we do frequently, and sometimes come home with 99.9 MPG on the meter. On the other hand, my 2015 GLS550 gave me about 13 MPG around town, and maybe 19 on the road if I was easy on it.