trade in when have financed car

Not really. I'm sure if you look hard enough you will probably find a shady dealer that will do it but you will be totally upside down until its paid off. Just don't go there.

You can and any dealer will be happy to do that for you. The reason is whatever you owe is just added to the new loan, whether the vehicle is worth more than you owe on it or not. So what actually happens in the end is you're paying for two vehicles, one of which you no longer have. Unless your current, financed vehicle, is falling apart keep it until it's paid for. Then trade it in or keep it until it is falling apart. You'll be much better off in the long run! Hope that helps! Jim