We booked the Renaissance London Heathrow Hotel for one night prior to an early-ish departure from Heathrow the next morning. This hotels car park entry is not that obvious to find and is protected by a boom gate requiring one take a ticket to enter.
At check in I was served by a person with a couldn't care less attitude but we got there in the end and I was told as long as I exit the car park within 20 minutes it is free. Dropped the bags in the room and went to exit the car park to take the rental car back to the nearby Avis depot and the ticket would not open the gate. Went back to reception and another person validated the card in a machine so we could exit!
We had something to eat at the bar which was ok but the service was average and had an early night. The room was fine, roomy enough, and clean.
It cost 18 Pounds to get a car to Terminal 5 the next morning from this hotel, it was meant to be 15 but the driver asked for more because we had bags!