But John, you know what you are doing. The OP may not and doesn't want to.

So, apart from checks and oil/filter changes, there are brake fluid changes, Manufacturer service bulletins to be carred out and the overall goodwill if something does wrong outside the warranty period.

Personally I would keep with the main dealer servicing for another three years, but get any major work (e.g. brake discs and pads) done at a cheaper specialist using branded parts only.

If it's a genuine VAG specialist with VW qualified techs (i.e. ex main dealer staff), who use genuine parts and the correct oil they will do an as good or better job. It's not always less money though, so worth getting quotes from both.

I was so unimpressed with the two Seat dealers closest to us, who seemed incompetent and disinterested in so many ways whilst we were trying to buy my wife's Leon, I wouldn't have wanted to use either of them for the servicing. This meant it was either travel 60 miles each way to the (very good) main dealer we eventually bought the car from, or use the local VAG specialist who is just down the road (which is what we did).

However, that specialist was a company we'd been using for years on older cars and prior to that I'd heard good things about them from work colleagues who also used them. I definitely had confidence they knew what they were doing and properly followed the correct schedules. I wouldn't have done the same with a company who claimed to be a specialist who I'd just found in the phone book or on Google.

Nothing went wrong with the car during the warranty period, so I never needed to try using the theoretical ability to claim on the warranty without main dealer servicing, and it's now 5 years old with 55k miles on the clock still with no issues.

Try calling the nearest specialist for a price then call your main dealer to see if they’ll match it or get close. My local VW dealer will discount if you do this and the marginal extra cost is more than outweighed by the additional value your car will retain with a full dealer history plus you may see post warranty goodwill from the dealer and manufacturer. I certainly did on my Polo with a couple of out of warranty repairs done foc.

Thats significant consideration, particularly for recent VAG cars where they seem to develop serious faults just outside the three years. Even if they don't pay the full amount they will often make a substantial contribution. I saved £1000 ( 75% ) on one occasion with this. There are loads of technical updates that only main dealers can do. Up to 5/6 years old I stick to the main dealer.

"I used a so-called local BMW specialist once"

So did I, they tried to tell me I needed a new catalytic converter on an old BMW when I didn't. On a related question, I expect I'll be asked if I want to buy a warrenty extension; I'm sure I'll need to read the T&Cs very carefully to determine if it's worth it?