I have a 2007 Audi RS4; it usually refuses to start when I leave it to cool down. The agents have changed the starter relay and it still does the same thing. The starter doesn't turn and I can only hear the clicking sound from the relay. I usually press the starter button continuously for about 30 minutes until it starts.
My car has 180000 miles.
My car has a manual transmission.
If you can hear the relay clicking, then you may have an issue with the starter. Starters often become tempermental before they fail altogether, so the trick is to diagnose it while it is in failure. If you can access the starter solenoid, there is a terminal marked 50 that has a ten gauge wire connected. This terminal needs to see about 10 volts in order to activate the starter. If the battery is fully charged, and the cables are good, and there is ten volts at that terminal, the starter should be turning. You can get someone to check this for you by contacting Your Mechanic. They will send a technician to your home or office to check out your starting problem and let you know if you need a starter or what.