To get to Hertz’s Heathrow desk you will need to catch the ‘Car Rental Courtesy Bus’ which stops at each terminal and will drop you off at the Hertz desk free of charge. The bus stop numbers are
Terminal 1: Bus stop 5
Terminal 3: Bus stop 21
Terminal 4: Bus stop 26
Terminal 5: Bus stop 18
The bus takes around 15 minutes to get to terminal 1, 2 and 3 and 20 minutes from terminal 4. You can catch the same shuttle bus after you have returned your car to get to the departures terminal.