I appreciate that RBR is a sacred cow for many people and I have the greatest respect for all the fans whos hard work has kept it alive all this time. Personally though I spent much more time installing it than I did playing it as I just couldn't get to grips with it (apologies for the pun). No doubt I will get a lot of stick for this, but I consider the Rally content of GT5 and GT6 to have been pretty good, although maybe the lack of grip was slightly overdone in the same way that it is slightly underdone in DiRT Rally. It's a real shame that Sony/PD abandoned the Rally aspect of GT in favour of ripping people off. If DiRT Rally could do an even better job than GT in terms of handling/grip/surface emulation that would fall somewhere between GT5/6 and what it has now then I feel sure the game would be a winner. These couple of videos show the fun to be had Rallying in GT5 and 6. The cars were specifically setup for maximum sideways action, which isn't the fastest way round a stage, but it's quite entertaining.
https://youtu.be/Tnu_oQn7sgg https://youtu.be/m97d3U36y3E (sorry, I can't get them to embed...)