I wonder who could be the main driver of a lowered Civic with alloys, loud exhaust and all the other gubbins. The 19 year old lad 'named' driver or the middle aged housewife 'main' driver. Hmm, tough one that...
Well all that "gubins" is probably not insured through their company legitimatley otherwise their premium would be through the roof anyway. So whether they are fronting or not, their insurance is most likely void in the case of a accident.
Why don't you just let your mum drive a bit more? Get her to do the weekly shop in it and a few errands when you're doing something else so if you ever do get in an accident you won't even have to lie and you still get money off your insurance.