I bought an VW T4 transporter a few years ago, the previous owner was a heavy smoker, after a cleanup of the vehicle, I used an air conditioner treatment and left the car running with the air conditioner running in recirc. I also left used ground coffee beans in the car for a month in the bag opened, summer helped with this as well.
carpet cleaned and cleaned the seats, and replaced the hood liner, I googled the crap out of this and the end result after the coffee smell went away, and there was no more smell of cigarettes, the windscreen always seemed to have a greasy look from the inside though.
I wanted to do it on the cheap, but not wreck the damn thing.
cheers
AdrianW