You are still within the six months legal protection but depending on when in Feb you bought it, this will end soon. You may have to act quickly if you need to reject the car. Doing so solely on mileage reduction may be tricky. Others may know for sure but I don’t think that other faults that have been satisfactorily repaired are relevant legally - although they add to your case to the dealer that it’s not acceptable to have had multiple issues.

Back to the fuel issue. Are you measuring fuel by brim to brim (The best way) or by the onboard computer? If the latter it’s just possible its faulty. My Golf offers three readings - long term, since refuel and since start. Is the Passat the same? That might offer evidence that the fault was caused by their recent work.

You might as suggested get another dealer to check it but bear in mind you are then introducing a third party to the case and AC might claim they caused the issue.

if it was me I would formally write to the dealer principal stating my case and reserving the right to reject if they cannot resolve. Having legal rights is one thing exercising them can be trickier if it’s something with an element of subjectivity. Keep calm and polite but firm and you may not need to resort to a legal route.

Edited by catsdad on 29/07/2020 at 13:26

Is it worth trying another VW dealership for a second opinion?

I can't speak for VW but my experience of the differences between some Peugeot and Kia dealerships over the years I wouldn't trust some of them to check the tyre pressures

Indeed - car main dealers vary considerably in quality, and not just from one area or franchise to the next. Some are very good on sales but useless on the maintenance side of things. Sometimes its because of lax / poor management of the service dept or a specific mechanic.

Some makes will invariably have more poor main dealers (and especially servicing / parts dept) than others, which is why the likes of Honda and Toyota/Lexus do well on customer service ranking.