Or, you could actually put a substantial enough down payment on the car so you aren't upside down. In other words, if you could actually afford the car, then you'd never have "negative equity" in it. You couldn't afford 3 of those 6 new cars. Use your head, "I'm upside down on a car, so I know, I'll buy a NEW depreciating liability (it's not an asset or an investment, it's a liability) with another huge depreciation hit, and I'll "hide" the negative equity by rolling the extra $Xk I'm upside down on into the new loan because they are having a year-end sale so I somehow believe I'm making a smart financial decision because the negative equity will hopefully disappear into the year-end savings on the next one!" No wonder you people in America have such a credit crisis. Borrowing to the hilt on crap you flat-out can't afford. Save some money for a down payment, buy a car with enough down that you aren't eating out of a dumpster the day you drive it off the lot, stick with it for the 3-5 years until it's paid off, and after just 3-5 short years of paying it off, having had a substantial down payment, you should have MORE than enough to put a substantial amount down on the next one, that being the value of the car you own that is now paid off but still only a few years old.
No offense, but from what I've seen here, half the people in these new 5.0s on this site are ass-upside down on them and actually can't afford them. I've seen so many people rolling upside down loans from the previous $35k car they couldn't actually afford to begin with into these new 5.0s, like upwards of $6k-$7k negative equity. Yes, let's take a $41k-$42k loan for a $35k car that will be worth $30k before it ever rolls into my driveway. Talk about colossal stupidity.
If you are buying a $35k car, you need a minimum of about $10k down to cover TTL to more or less just break even after driving it off the lot. $10k really isn't enough though if you think about it, because even if you are even when you drive it off the lot, it's going to depreciate at the same rate or faster than your $500+ payment, particularly if you're planning to lose an extra X thousand by trading it in down the road rather than selling privately. $15k would better put you in a safe zone, and IMO would be the true minimum you'd need to put towards the out-the-door price on a new 5.0.