Dirt1 - physics is bad and cars weigh like a bigmac.
Dirt2 - great physics, "arcade but belevable" OR "correct but simplified", all the tricks that work in RL works, can use the weight of the car to flick or use weight of the car to get stability in the high speed stuff. "I can't beleve this is Codemasters"
Dirt3 - horrible physics like Dirt1, no need to use the break pedal EVER, car weighs like a lollipop so hairpins are taken more or less flat out with a touch of the breaks and hand break to spin around. "Same old Codemasters"
Also the menu system is slow as an UF1 with cool effects that are cool the first time and annoying the second, and a long unskippable cut scene before and after every race.
Edit: tried to run Dirt3 with wheel, just annoying the FFB is a scam and why use pedals when they are full on or nothing anyway.