well, i drive 12-16 hours a day everyday, but last car i had was a 3000gt @ 360hp and weighs similar to challenger. Didnt seem all that fast to me due to the car being heavy. Figured i could do with a few extra horses, But turbo/supercharger kits are like 5k or more alot of the time+ having to do alot more to a motor. Really not sure what kinda gas mileage i can expect on v8 small block/big block. In my mind id only want better gas mileage to save a few bucks, but really if im having to dump in an extra 5k+ its not really worth it.
With all that being said, i can put 100k+ on a car in a year or two since i love driving. Things that factor into the equation for me in a motor choice are, reliability, Moderate amount of HP and fairly decent gas mileage. Anything i drive is gonna see alot of HWY and local driving, but im not a speed junky by any means, esp around here where the speed limit at most is 45 and usually 25 due to heavy foot traffic.