I highly doubt you can upgrade the video card in the laptop. In nearly all cases the video chip is soldered into the motherboard. Those very, very few laptops which allows you to upgrade the video card are usually in excess of $1,500+; easily. But not all of those have replaceable video cards either, so you cannot just go by the cost of the laptop. You would need to research if in fact the video card could be replaced.
Laptop video card are not sold to the general public so you would have a difficult time looking for a card that would be compatible with your laptop.
Forget upgrading your laptop. Just get your car fixed, then save up money for a new desktop PC.