Even when a hard inquiry is "illegitimate" -- for example if you contact Verizon for pricing info about a cell phone plan and they promise you that they will only do a soft pull -- it's virtually impossible to get a credit bureau to remove the inquiry later.
But indeed it sounds like all of these inquiries are legitimate. Your friend really was shopping for a car, the friend really did give these multiple dealerships his SSN, the dealerships followed typical practice and shotgunned the request to many lenders in an attempt to get the prospective customer the best deal.
In theory, if all of these dozens and dozens of auto inquiries were made in the same 14-day window, your friend's FICO score will treat them as if they were only one inquiry. (If some of the inquiries failed to be coded as Auto, however, that could screw up that "de-duplication" and FICO might see them as separate.)
Worst case scenario is that FICO will ignore any inquiry after one year, so I would advise your friend to not worry about it,. But also use it as a teachable moment, so that if your friend doesn't want this to happen again, he should secure his auto financing separately (e.g. at his local credit union) and explicitly refuse to give his SSN to a dealership and also tell them not to investigate financing.
