Was jump starting a friends' car today with my R32, which was idling away at 600rpm, and the car in question was having a bit of bother starting (its HT leads don't like the winter).
After a couple of attempts at starting, my cars' idle increased to about 900rpm and it stayed there for about 30 secs after we started the other car and took the jump leads off.. I'm guessing the mk5 has some kind of electrical system that knows to increase engine revs if there's a heavy load on it? You learn something everyday