best bet is swapping super low rolling resistance tires, a belly pan of some sort to smmoth out under aero as much as possible. significantly lowering the car (by 2 inches or more) and putting a rubber lip on the bottom of the front bumper to further cut down on air getting under the car. also may have to make functional fender vents and rear bumper vents to help get rid of the high pressure zone in the wheel well cause by the spinning tires
apart from downforce generating wings (which arent needed here) its basicly what people do for track cars.
your car will never be like my car, after all you have common sense......