how could solar panels power a car and how would you get the most energy out of it (im talking about school project model cars)

The solar panel charges a battery. The battery powers the car's electric engine.

 

Does that answer the question? If not, I kindly request to ask some more specific questions.

 

Solar panels are most efficient if they are perpendicular to the incoming sunlight.

You can probably get away with leaving out the battery if you do it right and have decent sunshine when you demonstrate it.

Maybe put "wings" on it with solar panels that resemble how satellites look. Except you would turn the wings 90 degrees so they're parallel against the car. (Satellite image example in the link below)

 

http://upload.wikimedia.org/wikipedia/commons/8/8d/GPS_Satellite_NASA_art-iif.jpg

Fashion wings with solar panels to act like spoilers and cover the body of the car with flexible solar cells.

The Nuna team has won the solar challenge 4 times in a row. It's a race through all of Australia, on normal roads (meaning there is also other traffic).

 

Note that this winning car has no solar panels on one of its two sides (because the race is from north to south I believe). It also has no spoiler. It simply has maximized the surface flat area on top and covered that completely with solar cells.

 

check google pictures for:

nuna 4 winner solar challenge