Recently the car has been giving the impression of a flat battery when trying to start. It would turnover a couple of times but very very slowly. Turning the ignition off and then on again and the car would turn over slowly and then speed up and start but this may take a few attempts. It gave all the impressions of a poor starter motor. But having fitted one on a previous Q7 I know this is a 4 hour job and even with a decent discount is still over £200 for the unit. So decided to ring a local auto electrician that could hopefully diagnose exactly the part that needed replacing. (Vagcom showed nothing amiss by the way).
He turned up and checked the car over and said that the cars alternator was charging the battery at around 13.6v. This is a indication of a poor earth and fitted another earth cable from the earth point under the bonnet used for jump starting to the engine manifold. Said he’s fitted loads as it’s a well known problem within VAG that the earths corrode over time and need cleaning. The car now charges at just over 14v and starts better than it ever did less than 2 seconds from turning the key. Turns over faster than my mates 2011 and 2014 Q7’s. Cost £10 for the earth cable and £40 for callout Including 1 hours labour.
Hope this is helpful to anybody with a similar problem.