We arrived at HERTZ earlier than the scheduled time, and the reserved car model was not available. The staff said they could only offer an electric car or a manual transmission car unless I paid double the order price for an upgrade. I declined and decided to wait. After waiting for nearly 2 hours, another experienced staff member managed to provide me with an SUV one size smaller than what I had reserved. I had booked a small SUV, which was supposed to fit three 24-inch suitcases in the trunk, but they gave me a compact SUV that barely fit two 24-inch suitcases. After placing the luggage, there was barely room for even a large bottle of water in the trunk. Having rented cars internationally five or six times, this was the only time a rental company downgraded my car model. The service at HERTZ Heathrow Airport branch was really disappointing. The car itself was in good condition, quite new, with only a few thousand miles on it.