1994 Chevy Beretta Gas/Oil smell in cab and outside car.

We have inherited my fathers old 1994 Chevy Beretta. The car runs beautifully, and starts up with no problems. Before he gave it to us, my Dad had the fluids changed, hoses replaced, new battery, and the engine cleaned. My concern is the persistent stench of gasoline or oil burning inside the cab and outside. The fumes are not enough to not drive the car, but it is concerning that it remains. Also, those behind us can smell burning oil. There is no visual burning indicators, such as smoke. There is no dripping of fluids while parked. Yet the smells persist. What should we be concerned about? How can we find the problem and fix it? Dad seemed to think it was some cleaning or oil solution that was spillled on the engine, however, after having driven the car over 300 miles to get home, should this excess fluid not have been "burned off" by now? Need help!