Is £5k a very good price for the car? If yes, that's a scam indicator. £5k for an Audi does sound like it could be too low in the current market.
Some time ago, DP found a version of a car he was looking for in Gibraltar, slightly into suspiciously cheap price range and they were offering to ship to the UK, claimed they'd moved out there to live and now wanted rid of their UK car, hence selling on the UK market.
They made all the right noises about secure payment but DP told them, it's OK, my mate lives in Gib, so we'll fly out, stay with him for the weekend and then drive the car back. Surprisingly, he never heard from the seller again.
Tell the seller you've sorted a lift to come and view the car and ask about arranging that. If the seller is trying to scam you, they'll suddenly lose interest.
If you genuinely want to buy a car remotely, look at Cinch, Cazoo or a car supermarket with multiple branches who will move a car closer to you to do it safely. Don't gamble thousands on Gumtree.