i was over 2mins ahead on snow(evo rally car), the same for tarmac(i used a s2k race car), but can't get anywhere on dirt...same problem for the loeb challenge. I rocked the dirt in GT4, so i dunno what changed.
I'm the same, easy golds on dirt and snow, on tarmac I'm using a TVR Tamora, 345hp / 1060kg or so, and I'm not even remotely close. Not making any huge mistakes, not as quick as I perhaps could be, but I'm a looong way off.