Car Hire at IAD

Advice needed please. Which car hire companies - if any - are on-airport at IAD or do their locations mean that I will need to lug bags on and off the dreaded shuttle bus?

AFAIK they're all off airport, next to each other on Autopilot Drive, with shuttle buses from the terminal.

All off airport, and I did once rent a car to go from IAD to Reagan via the excellent museum nearby. Was cheaper and more convenient that taxi's and allowed me to use the metro to go shopping, as I just left the car in the AVIS depot with my bag while I went to the Mall.

They are 100% all off airport as I was there not that long ago again.
Its the normal walk outside and wait for the bus kind of thing.
Take about 15 min from airport to Rental area. The walk is only 60 seconds from the terminal doors.

Thanks for the replies guys. As we won't need one straight away, have decided to go 'carless' for the first few days (after sampling the delights of UC for the first time from LHR) and pick up a car from Union Station just before we leave DC on our road trip.

Thanks for the replies guys. As we won't need one straight away, have decided to go 'carless' for the first few days (after sampling the delights of UC for the first time from LHR) and pick up a car from Union Station just before we leave DC on our road trip.

That's exactly what we did last year. Got a cab to the station and had a car within 20 mins of arriving at the desk y)