MB have released their new 2016 GL class SUV in traditional wagon and 4-door Coupe versions.
What I found interesting was the two different rooflines. So I looked up the fuel consumption figures for both models in the GL400 class (twin turbo V6 gasoline engine with auto and AWD).
So MB has quoted the 'slippery' Coupe as only 0.1lt per 100km better on the combined cycle. I know the difference would be noticed more at highway speeds, but I couldn't find a highway only figure for the upcoming Coupe version.
Would have thought the better aero shape of the Coupe might have yielded a bigger difference even in the combined cycle??
Still, at 8.8lt (Wagon) vs. 8.7lt (Coupe) per 100km its hardly a thirsty SUV. Albeit, claimed manufacturers figures ;-)
No doubt those tests took place on a rolling road in a laboratory, sadly they can only estimate and calculate other factors like weather/wind resistance etc in such conditions. No doubt in real life, a more aerodynamic shape will have a bigger impact on fuel efficiency, having said that, the vehicle in question is a large SUV, it's high up so it's aero drag is higher than a normal car.
Yeah, the specifics of the official test will affect if their is any official difference. Most of those tests likely don't reach a speed high enough for such minor aero differences to be seen. That coupe also needs a belly pan and grill shutters to get a better improvement over the SUV.
Does Australia have their own test protocols, or do they basically just use someone elses(Japan, US, or EU) test methods or results?
A lot of manufactures are now focusing on aerodynamics and weight stripping. Up until now, all the development has been in engine technology, but manufacturers are beginning to realise that the lab tests they do for fuel consumption, aerodrag etc can only be estimated, and having a nice fuel efficient engine can be ruined by sloppy aerodynamics or unnecessary weight! We can learn so much from the Motorsport industry