Yes, you only get the limo/volvo on the highest paid tickets (J and D ?). The drive-through check-in at LHR is great but not worth the extra thousands compared to a Z fare. (and you can still use the Upper Class wing at heathrow anyway - you just take the lift next to check-in)
The only other difference is you will earn more flying club miles now on a full-fare UC compared to a discounted fare. Otherwise I think everything is the same.