The court will try to figure out the fair market value for the vehicle. Using www.KBB.com is a common practice and usually gives a realistic value.
The court could order the vehicle sold or for you to pay the other side one half of the value. Hopefully this will balance out with the cash accounts and other property issues.
The court probably won't order you to sell the car but will probably award the car to one person and offset this with an award of some sort of CP in equal value to the other person. The most common method is to use one of the internet web sites such as Kelly Blue Book.
A photograph of the car showing that it is very used could be helpful. The other answers refer to the website, KBB.com, which is fine. From what I've seen in settlement conferences, the actual little blue book (Kelly Blue Book) will be pulled out, and the mileage, condition, and whether there are any add ons to the car will be discussed / argued. Cars are rarely ordered sold; instead, the value is used to calculate an equalizing payment, so if the car is used and needs new tires or needs its transmission replaced, you should be ready to tell those details, and possibly even prove them up.
As stated above -- I have NOT actually stated any legal opinion, because I need to know more before I can start to form one.