After this many posts, you still have not said anything about how much the car in question weighs, its rolling resistance, or its coefficient of drag (with reference to wind speed). Are you beginning to understand why nobody can guess what size solar cell to use, or what size battery, or what size motor? It takes several calculations to come up with those numbers and it's all a matter of balance between size and results. You can waste a lot of money by guessing.
So, best wishes for your exploration of this subject. A lot of people have been there before you; learn from them!
So, best wishes for your exploration of this subject. A lot of people have been there before you; learn from them!