[Jamo]

Do NOT leave your car at the lot and even threaten to cancel the insurance or stop making payments. Work with the dealer/owner and area rep. You're a LONG way away from any application of typical Lemon Laws.

You're under a seperate contractual relationship for paying for the vehicle, and the lease or purchase agreement requires sufficient insurance coverage. If you threaten or commit any such conduct, you are providing the dealer and finance company with the doctrine of unclean hands (at the least) or breach (or grounds for anticipatory breach) of the purchase and finance agreement.

Basically, your threatening to take a hammer to your own left nut if they don't do what you want them to. Very likely they will sit back and wait for you to pound away.