There is no way to detect it, period.
How does a computer, through math alone, determine the difference between...
1) Wrecker never touches the brakes, slams you in a hairpin...
vs
2) Wrecker waits off track, then pull in front of you, causing you to hit him.
vs
3) You spin, pull saftely out of the racing line as cars pass, and a wrecker intentionally nails you.
In case 1, the wrecker is the much faster driver.
In case 2, the wrecker is the slower driver
In case 3, the wrecker is the faster driver, but how do you know hes a wrecker or not, he could have just started a pass and not seen you till he pulled out from behind someone.
There have been things like this in other games, and heres what always happens. Some wreckers get kicked, yes. Alot of honest races would too. Even the spin detector, ive been spectated before for clipping the wall coming out of the chicane at SO.
LFS needs to implement a global "rating" system. Not a points system like some of the leagues do. A rating system, based on wrecks, restarts, etc... and allow servers to set ranges of ratings... That way, people end up playing with people of their caliber. The catch to a system like this is that LFS server controller would have to look at servers, recognize that everyone is set very high and there is no races for low-rank drivers, and would have to let them temp have a higher rank, so they could race...still better than nothing though. Either way, if you were bad enough, you would have a hard time finding a fun race.
Another option is "conditional ghosting" ... ie, your closing rate on a car is too high, you pass through them. Good racers are rarely going to hit another racer at high speed difference, so for those of you serious enough to complain about the realism(lack of) of ghosting would never be effected by it... That way, the guy that plows turn 1 cant ruin the race for others...or the guy that pulls out in front of the leaders cant either...
Creative ideas are needed for these kinds of problems, as computers cannot make objective descisions.