I know that there has been much discussion about driving with your windows up or down and how it may affect fuel economy.
My question is almost the same... how much does driving at highway speeds with the sunroof open affect fuel efficiency?
not enough to worry about
That is correct.
You wouldn't tell the difference. Most modern sunroofs, like my 2020 Accord for example, retract inside the roof and not externally like they used to. They also have plastic air diffusers that pop up at the front of the opening to guide air over the open space.
A lot of wind tunnel work has been done to achieve the lowest drag coefficient possible. On a modern car, you are looking at a difference that's nearly immeasurable.
@Mod_Man Imagine people say that opening sunroofs improve aerodynamics :0
These days, you never know what they'll say next. {black}:scared:
