I want to buy a 2013 Dodge Charger with
120,000 miles on it. How long will it most
Don't even go there, these things are run hard and abused to no end, most never see 150000 without some kind of engine and or transmission work. Want more information just check out you tube.
And How much would engine and/or transmission work cost?
Depends on where you have the work done and just what went bad, roughly between 3 to 8 grand, sometimes more. If it's to far gone most just scrap the vehicle or get used parts installed and then trade it in.