Yes, I agree that MR cars are different and don't reward an aggressive style, but GT5 had a big physics change for online around autumn / the end of 2012, which increased the grip and stability online.
This meant that specialist websites that catered for those who liked the MR feel / driving style that was beyond the normal or average (i.e. used cars like the stock Yellowbird etc) had to reduce the tyres they were using to try and get the same feel, but still complained there was too much grip and stability.
Before this change, people who didn't have ability to drive cars like the stock Yellowbird, could do so through tuning the suspension and LSD, after the update this tuning wasn't required and driving the Yellowbird stock, online, was much easier.
When I started iRacing, the Ford spec racer was a bit of a handful, but again, through tuning it become much more drive-able.
But now with GT6 - even through tuning, some cars are still having snap oversteer, even when quite extreme tuning is applied, more extreme than what was required to drive cars like the Yellowbird before the update gave greater stability and grip online. One of my friends who races with a specialist website for these cars was saying that his favourite car from GT5 (RUF RGT, stock, comfort tyres) had alot more oversteer, to the point where he felt it was almost too much.
This is what I mean by it not being quite right.
If you like these type of cars, you might like their races/racing. I'll have to speak to the site staff as to whether refferring you to them would be seen as soliciting, if the site staff are OK with it, I'll send you their details - let me know

Click to expand...