I drove my A3 2500 miles home last year.
If they said, "running or driven onto lot" ask them to have it running when you get there. Mine said running and I told them I had to see it start and run when I got there, since the auction was for a running truck. I was quite happy to see my truck idling away happily when I arrived.
My GL experience has been positive all three times I've won a bid, two locations, always helpful and nice.
Here are some A3 tidbits.
You won't need earplugs as much as you might think, the noise inside the cab is easy to talk over. If it rains your feet will get wet, water drips over the gas peddle in every deuce I have driven lately. Bring a pillow for the passenger, that seat is tough on asses after a while.
If you had a chance to get something serviced, I'd change the trans from motor oil to dextron as soon as possible, the army uses motor oil, it runs hotter. If the transd temp guage does not work, bring a digital volt meter with a temprature probe and stick the probe down the fill tube to check oil temps.
Have a phone number for a commerical tire service or tools to swap a tire, if you are missing the jack, go buy a 10ton hydraulic and find a few decent blocks of wood, make sure you have tire chocks.
My truck ran like a champ, expect 48-50mph base speed on where the truck rides with as little hopping as possible. 55-60 is a dream, to many revs. I ran approx 2500 rpm, 12 hours a day, five days straight with ZERO problems. Expect something to dribble a little oil.
Expect tires to leak down, check them daily in the morning. Don't be suprised if the CTIS does not work. Buy an air serivce line that works off the glad handle from a local truck parts place, they run 20-30 bucks tops. Northern Tool has them as well.
Get a can of PB Blaster to get anything stuck or rusty moving. If the steering does not work, check the valve on the firewall.
Download manuals, the -10 operators manual is your friend and a great read on airplanes.
Expect the wiper blades to be toast, napa has commerical replacement in a pinch, they are about 1 inch to long but work.
Bugs don't die when they hit the window , they land and fly away later,,,,hahaha.
Make sure the blinkers and mirrors work, people never let you in, when you get room, start moving and they will learn not to try running a 6 ton truck off the road with a Honda. Headlites should work, learn the switch position on the three-handle switch.
Depending in the legal aspects of the trip, buy a three-day tag for you truck AND insurance from somebody. I had my stuff with me and had zero problems. Nobody stops mil truck anyway and I drove past a lot of weigh stations, since I was not commerical, hauling anything or had a reason too. Not that anyone cared, but I was prepared to answer questions, prove insurance, prove tag and my truck was road worthy.
Big trucks are supposed to have three warning triangles, first aid kit and a fire extinguisher on board. Buy them and put them under the seats. Buy a large fire extinguisher just in case you need it.
I posted my road trip here and had contacts within a couple of hours most of the way. Several guys followed my adventure online, one guy drove two hours to inspect the truck because wanted one for his farm. SS is your friend. Be prepared to chat at the fuel pump a few times. Farmers in the Dakotas loved the truck.
Your truck fits under a standard fuel station awning btw. Plan ahead for turning around and backing out. You can buy fuel at places other than truck stops.
The fuel gage sucks, mine has five quarters and bounces. I stopped and refueled every three hours or so and it took half a tank. I wished for a radio, even comm chatter from a .mil net would have been interesting,,hahaha.
Good luck, post pics.