I would vote the '18 style vw gulf as being the most awkward to get at, very small space to get the film through.
Being a one man show, many years ago I standardized my prices instead of trying to keep track of the window configuration of each car. A pair of doors was $---, as well as, all two door cars had a set price and and all 4 four door cars had a set price. Trucks varied based upon the model configuration. Even though some model are more difficult then others, now a days you can get a 4dr 5 window vehicle up to a 4dr 11 window vehicle it still feels easier to just say "all four door cars are $---". I think customers feel better knowing that they are all paying the same. After 30 years of tinting nothing is really difficult anymore, some vehicles just take a little longer, its really not that much in the grand scale of a career.