Sometimes, no assistance is needed at all. Why not spikes in the steering whell? Because they don't want their significant other to die as a result of an uncaring suicidal ghost driver aiming directly at him/her: IOW too much risk of collateral damage.
As for truck skirts, locally-maintained (read: poorly-maintained due to budget constraints) roads and especially railroad crossing are notorious for issues of ride height (so bad sometimes trailers can get STUCK), which means many need their full unobstructed undercarriage just to complete their trips.
Biting the hand that feeds IT
