Ditto….I’m going to run my own tests, just out of curiosityI won't have time to let you know. It's one of the next purchases for the truck when it arrives in the next week or two (already have a box of stuff to put on her when she gets home.)
But I want a tonneau for a few different reasons, none of which involve range/economy.
1) I don't want my truck's bed to be a convenient trashcan for other people
2) I am not driving my truck around in the winter with a bed full of snow and ice that will begin flying around said bed as it thaws and melts.
3) I like the look of most of them.
I have owned 3 pickups, with the Lightning becoming my fourth soon. All have had/will have tonneau covers. I've found much utility with them, and doubt that I would have a truck without one.