would anyone know the type of gas mileage on this car?

Well, I found this (http://www.fueleconomy.gov/Feg/noframes/1760.shtml) in about 5 seconds on-line:

5.0 liter, 4 spd auto:

Fuel Type
Regular

MPG (city)
15

MPG (highway)
23

MPG (combined)
18

My guess is mileage for a 5 spd manual transmission may be slightly better.

I have an '85 Camaro, I get 23 mpg...
(305 TPI 700r4 auto, all synthetics, 90% highway)