That has really varied for me over the years. I'm probably different than most car buyers. I've never owned a brand new car. I've had a few new bikes but never a car. I wouldn't lease on a bet (that's just my preference), I wouldn't rent a house either. I pay cash when I buy and I try to buy cars that are 1 to 2 years old from private individuals when possible though I have picked up on a corporate buy back from time to time. I won't buy one that has more than 20K on the clock. That particular age means it's taken it's major hit in depreciation and I'm not paying the premium price. Assuming it hasn't been crashed there isn't too much they could have done to hurt it in that time frame and of course I look them over with a fine tooth air gun before buying one.
I always buy the current model body style also.
I keep a vehicle until it's time to sell it. Sometimes that means a year and I've had an old Mach for as long as 20 years. In most cases I sell a vehicle when someone asks if I would sell it to them. Assuming the price is right it's time for me to go shopping for the next ride. This method has worked fairly well for me, it allows me to drive a relatively new car and I never have a car payment. It also means I've never had to preform a major repair on my own vehicle unless I've wanted to put in a hotter engine, lower set of gears or something like that. I keep them clean enough and have bought smart enough that on two occasions I've driven a car for over a year and sold it for the money I paid for it. If you can drive a car and only pay gas and oil for the time you drive it you're doing something right. Sometimes saving the money to pay cash for the first car is difficult but the formula has worked well for me. I probably keep my cars on an average of 2-3 years.
You have to be willing to suck it up from time to time when using this method because sometimes a good buy isn't your favorite color or option group. Of course you have to buy a car that meets your needs none the less. It's also important to remember that the best time to sell a car is when it's looking good. Don't wait until it has a few problems that you don't want to deal with, nobody else wants to deal with them either and you won't get top dollar. It's actually been a while since I bought a car for myself. The last four vehicles that I have driven have been trucks. I have two presently one is 4 years old and the other is an 06 that I picked up a month or so ago. My wife's Lincoln is an 05.
- actually, that was due to an oil change done at Jiffy Lube - engine seized the next time I drove it - seems they weren't too particular about tightening the drain plug
He would go in with the cashier's check, pay it in full and drive off in his new car,usually cadillacs. 
