Yes, there are. Follow the instructions below. There are many more rental cars suppliers on the La Linea de la Concepción side of the airport ( Spanish side ). It is a short walk away, across the border. Many people choose to collect from the Spanish side as it avoids any car queues there may be crossing the border. Wether you collect your hire car Gibraltar or Spanish side, your rental car will have Spanish plates and can be driven in both countries.