A good way to get your perspective to improve on this car:
First, draw a three-dimensional rectangle. Make sure it is about the same size as you want your car to be. Maximum height being the very top of the roof. Minimum height being the bottom of the body.
Second, Apply the wheels. make sure you've got your wheels centered on the bottom of your rectangle, so that they may appear to fit the vehicle properly in the long run.
Third; It is common for one to draw the lines of the door as harshly as if it were a primary line of the car. Try to avoid this, as it may distort your final product. The door will end up coming out of the shading as time goes along.