I'm a bit the same, I put in GT6 every now and then but always turn it off after a race or two and go right back to iRacing
Not sure about the VW TDi I haven't driven it. I have used cars and tracks that come with the standard iRacing membership so no-one has to buy extra once they join. I the future there may be other vehicles added, guess it depends how popular the series gets. Heres hoping as I would love to add more tracks!