The EPA estimates for the 2020 GLS450 are now published on the government's fueleconomy.gov site. The new model will be rated at 19 city/23 highway for a combined 21 mpg. Ratings for the previous model seem to have changed over the years. The 2019 GLS450 was 16/22/18 and my 2015 GL450 was 17/21/19. In general, it looks like the new powertrain will get an extra 2-3 mpg, thanks to the new engine and the new 48-volt system.

 

Unsurprisingly, the GLS's 19/23/21 is almost identical to the GLE's 19/24/21. I got 24.5 mpg on 360 mi. trip last weekend in our GLE 450 doing 70 or greater a good part of the time. ECO mode allows some coasting (Glide mode) with the engine off, but it doesn't seem to make that much difference.

 

Anyone have 2020 GLS580 Numbers?