What determines MPG in a car?

The same engine in two different vehicles can get very different mpg.Once you put the engine in your MC you can figure mileage

V-6 was not an option in 1970. The driver determines how good the mileage will be. Put an under powered V-6 in it, and it will have to work harder to move the car, In all likelihood, it wont get any better mileage, than a well tuned small block V-8. If you are worried about mileage in that car, sell it and buy something else.

LOITS MORE! the FUELINDUCTION SYSTEM the FINAL DRIVE ger ratios, The AUTOMATIC gear ratios, SYNTHTIC LUBRICANT use a NEW GEN IV engein in there which is MUCH IMPORVED over the orignal desing from the FIFTIES they used for DEACDES! A FOUR BLOT MAIN engien from that time period was worth a LOT OF MONEY at one time, but they AL Lwere poorly balnaced and had THIN WALL construction. A TURBO BUICK engien woudl fit in there, and be MORE exciting and have MORE RELIABLE POWER! i do NOT really like GM engine designs! They are FUEL WASTERS<and usually NOT VERY EFFICIENT< but they are STURDY at least! A PROPERLY REDONE buick engine with a TURBO ONIT is about the best OLD gm had to offer! GOOD LUCK!! A prperly UPGRADED genuine 1970 engein with ELECTRONIC IGNTION from MALLORY or PE%TRONIX< wih a REAL HOLLEY and proper CAMSHFT CHOICES can be AWESOM and stil godo with gas (depending upon GEAR RATIOS and if an OVERDRIVE TRANNIE is easy to use or intall! GOOD LUCK!

Engine, transmission, drive train, weight of the car, aerodynamics, and more!