As a general rule for new cars, I was taught that if you can't put at least 20% down, NOT including any trade-in, and pay it off in 3 years, you are buying too much car, and you'll certainly end up owing more than the car is worth.
Jeff
You are dead on with that one!
I wish I could get down to 25K miles per year. Currently I am in the high 60K's per year.
I do buy new, but only finance for 3 years max. Then drive it for at least 5 years. During the "non-payment" years the previous payment amount is stocked back for the next down payment. I do follow ALL maintenance in the books from the factory. The vehicles would probably last longer, but I really don't want to risk it.