Can I sue my dealership?

It appears you had a lemon law claim. How you did not realize the trade-in value was less than what you should have received under the lemon law is unclear from the facts. You have an obligation to read what you sign. See an attorney to discuss the specifics of your particular situation to see if you have any recourse for failing to read before you signed.

You may have a claim under the Consumer Leasing Act. The potential Lemon Law claim disappeared when you traded in the vehicle. Your case could be very seriously helped if you had the original window sticker pertaining to the vehicle that you leased. These types of claims can be complicated so be sure to consult with a lawyer experienced in the area. Also, be aware that the statute of limitations on a Consumer Leasing Act case is only one year from the date of the lease.