Should I angle my car downwards or leave the slope at a level 0? I’m looking for the most aerodynamic car possible. Speed is a bonus, but distance is my objective, so I need a pretty good start and cant leave my car with a lot of stress on it. Is there a reason people angle wheelbarrows downwards or have smaller wheels in the front?

Looking for any ideas and if you do help, please explain in physics terms or just logic as to why your idea would make sense. I’m building a mousetrap propelled car btw.
*edit: just to clear it up, it will only ride against other cars on flat surfaces.
Thanks.