Joe wrote:

-snip-
If you don't mind paying for it, the better auto body shops have smoke
generators to test car door seals after repairs. You get results
pretty quickly.

My 3 stall local mechanic has a smoker.

A bee smoker from your local farm supply store is a
low cost generator if you want to go that route. The tricky part will
be rigging things so you have actual smoky air flow to look for
outside, since a static test probably won't do much.

He checked a trunk leak for me once. Regular charge for 1/2 hr.. He
smoked from the outside with his little helper in the trunk. He
mentioned another style smoker that has an electronic sniffer and is
much more sensitive.

The positive pressure hood that Steve mentioned sounds promising,
though.

Jim