I believe all vehicles built for F&F use a basic Chevy 350. They pull the motors that come in the cars and put the same motors and transmissions in everything to make it easier to work on. I watched a show about it once and thought it was interesting.
They all use the LS style of motors. I had forgot about that. Which in the flip cars in the 6th movie, there is a pretty good shot of the motor and you can clearly tell its an LS intake, but then later when the "gang" is back talking about those cars and trying to determine what they were. The say the motors were high revving import motors. Which was kind of funny to me, others I'm sure.
The charger I'm thinking of may have been built as a car for the movie but not in the movie. I just remember watching a video and reading about it. They were talking all about it and The Fast and Furious 7. Ill have to try and find it, it was a neat article and what all they did with the car was pretty cool.