Complex sentence: The chain was started in 1974 with several locations in the state of Florida, and earned public appeal for its "unlimited mileage" program, where people could travel any distance with the car at no extra charge.
Split into simpler sentences: The chain was started in 1974 with several locations in the state of Florida. It was liked by many because of its "unlimited mileage" program, meaning that people could travel any distance with the car they rented for no extra charge.