I have a 2008 black GTI so I know where you're coming from. I've tried several popular combo's of sealer topped with a wax and only once did I think it looked better - and that was CG Jet seal topped by CG 50-50. It's my opinion that it looked better since Jet Seal didn't look that good by itself. Other sealers like BFWD, Poxy, M21 etc never got any bennefit from a wax-topper (IMHO).
That said, if - big if, you used Autoglym HD by itself, I think you would like it, but be warned, it doesn't go on /come off nearly as easy as BFWD and it doesn't last as long and is no way as slick. But, the look is really something.
Hint - if you do try it, I cut a 5.5" LC red pad down to 4" to get in the AGHD jar, apply like polish with a PC, work it in hard on speed 3-3.5, then let it haze, and be prepared to use 3-4 big towels, folding often to remove.