YES. Can you be convicted? that's what you really want to know. The drugs are 1 fact among many too numerous to discuss in detail here. Get a free consultation scheduled with local criminal defense counsel and pick the one you want or alternatively ask that a public defender be appointed if you qualify. I am unable to address the class 1 felony since I am not familiar with WI laws.
A class I felony is the lowest level felony in WI. Off the top of my head, it's a 3.5 year max. You must have had a prior conviction for possession. This is a second and subsequent, right? They will have to prove that you had knowledge that the substance was there. If you didn't, they will have a tough time convicting you.
Absolutely, yes. It was your car and so they assume that it was your drugs. My colleagues have made great points. You need an attorney.
The information provided in this answer does not create an attorney-client relationship. If you are interested in his legal services, feel free to call Chris at (303) 409-7635 at his law office in the Denver Tech Center. All initial consultations are free of charge.