A friend of mine is freakishly tall (6’6" or maybe taller) and only fits inside big, gas-guzzling vehicles. He doesn’t have the scratch to upgrade to the hybrid SUV just yet, but he wants to maximize the fuel efficiency in his van. He is already looking at removing the unused seats, maintaining tire pressure/balance/alignment, and so forth. What I’d like to know about is making a custom belly-pan to cover all the nasty bumpy bits on the underside of his van.
(1) Will a large sheet of fiberglass, cut to size and bolted into place, serve well enough?
(1b) Will that actually reduce the drag at all?
(2) Should he drill drain holes anywhere?
(3) Is taping over the door seams going to have any appreciable benefit?