Interesting discussion. I have a GTI PP on order for delivery in late June (not keyless entry). My current car, an Audi A4, has gone through 2 key fob batteries in 18 months, giving me a dash warning each time. My A4 does not have keyless entry, but does have keyless start.
I was shocked when this happened, as I had come out of a BMW 520d which I ran for 5 years without ever having to change the key fob battery. That car was same as my A4, keyless start only.
Looks like a VAG feature that they burn key fob batteries, even on cars without keyless entry.
I will keep spare batteries in the GTI and my wallet, just in case I get no dash warning!