Is their a complete list that explains dirtylaps and what constitutes a dirty lap stuck on that?
I had the same question months back and searched a couple of threads discussing this. In addition, here is what I found in the FAQ
http://forums.forza.net/turn10_postsm67078_Forza-Motorsport-5---Game-FAQ.aspx#post_67078
Also…
http://forums.forza.net/turn10_postst643_dirty-laps.aspx
There are many other threads discussing such that you might want to check out. Good luck!
I have heard that bottoming out your car can dirty a lap. I have never seen it though.
Other than that, these are the conditions that will flag your lap as dirty.
Collisions with other vehicles
Driving off the track/Cutting corners. Please note that there are spots on the track where just getting one tire off the track will dirty the lap. There are other places where you can get the car nearly all the way off and it will still be clean. The more you drive a track, the more you will be able to see where those spots are.
Hitting a wall. Best example would be Bathurst. (There are times when you can lightly brush the wall and your lap will remain clean.)
Drafting. At any point above 100mph. Whether you are the one drafting or being drafted. Some one drafting you WiLL dirty your lap! (Please note that a draft can occur with a considerable amount of distance between cars.) Drafting is following or being fallowed. When you draft, both cars split the air resistance between them. As a result, both cars can move faster together. The idea of the leaderboards is to lay down your fastest time based on YOUR driving skill.
Please note that doing any of the aforementioned in the last frame of a lap will result in your next lap being dirty. At certain points around the track, the game gives your split time. ( green or red highlighted +/- time measured against your best lap.) The last frame of the lap = any point between the last split time checkpoint and the start/finish line. This does include the first lap. T10 did this so you can not cut a corner at the end of a lap to give you better speed starting your next lap which would result in a faster cheated lap time on leaderboards.
I am not sure if lag while in an online race will flag a lap as dirty.
Hope this clarifies any questions or confusion regarding dirty laps.
There is a certain track or 2 where you can cut a corner “legally” however if you bottom out in the process it will dirty the lap.
Thank you yeah i was wondering why my next lap was already dirty when know was around me and now know thank you very much")