Like many of you, I have been playing this game off and on since it came out.  I have 100 of the cars, completed many of the special events, and have all the race events open. I can easily place in group A in time trials in most cars, even without full upgrades. While this is the primary game I play, I am starting to fall out of love. The main reason is that the physics engine has lost its edge and just feels dead these days.   

1. Most cars now feel the same with little difference.  
2. Most cars set up with perfect balance with no push or oversteer tenancies, excluding the cars that just do not do anything well like the Ford GTs and Ferriari Enzo. The new Lotus 360 is a good example, the car stuck unrealistically everywhere. I just got a Spada, it is actually tail happy, the only car that does this.    
3. As long as the car does not slide, then it is about speed and line.  No worries about push or oversteer. 
4. If the car slides, it is always a oversteer slide. There is no push slide.
5. When the tail out slide starts: it is like the car stops forward motion, and does not let you correct by steering into the slide.  The car pivots then wants to be aimed a different way.  
6. There is no drifting ability in the physics.  
7. In some turns, if you slide off from overcooking or missing the line, you slide forever, even at slow speeds where it would not be normal to be able to slide.  This has gotten worse in recent releases, like there is a canned sub routine for killing your lap.
8. Sliding and brakes or gas makes no difference.  Once it goes, it just goes.
9. Track edges where "the clamp" on speed shows up is silly and is too close to the track.
10. The formula cars are ridiculously bad a slow speeds.  How can one of these slide off track 300ft at 60mph?   Once they slide they slide very weirdly.  A good example of how bad this is driving the F1 16.2 H2H at LeMans.  The chicanes on the Mulsanne straight require the car to slow to <100mph, the same as normal 30PR cars to not slide into the wall.  The Mulsanne corner is also ridiculous with having to go slower than most cars. 
11. Some cars have random braking performance that makes it hard to drive lap over lap consistently.  The F40 now has this problem for example.  

I doubt this post will mean much to the Monkey's but this great game is getting dumbed down and is no longer a challenge.

Ahh feel better now that I spoke my mind.
BB

PS Edit: I drive with no assists.