Insurance contracts are uberrimae fidei contracts which means they are based on utmost good faith.
They are voidable which means the contract is valid until such time as either party, generally the insured breaches it. All insurance contracts make clear to prospective and existing policyholders that where the policy holder is uncertain as to whether something qualifies as a material fact on which cover is based, they should consult with their insurer or broker.
How can an insurer be liable for an inreased risk he is unaware of at the outset of the policy? Where this happens the insurer has a right to terminate the contract ceasing to indemnify the policy holder against any claims against him which means the policy holder becomes PERSONALLY liable.
Despite the confusion, I think in this instance, the 18yr old has declared his modifcations but can only get inusrance on a TPFT basis as opposed to a fully comp basis. If this is not the case, as he has NOT declared his mods, then in the event of a claim where his vehicle were inspected and found to be at fault, then he might be looking at his insurer withdrawing cover for they would be perfectly entitled to do as explained above. He would then be personally liable to any claimants which could mean he would be unable to meet the liability resulting most certainly in bankruptcy. It happens. Criminal prosectution might also follow if death or serious injury were involved.
Starting out on the road is difficult for young drivers. For those of us a little older and wiser we should be a little more temperate and supportive toward the younger members of the fourm, trying to guide and assist those who might otherwise be an accident waiting to happen or skating on thin ice so to speak, not suggesting of course that this 18yr old is such a case. We were all young once, impetuous and impatient.
My advice to you would be to try to reduce your insurance costs, not to increase them by modifying your car. Get a cheap, reliable, economical car for £200 (yes you can get them even for £100 with MOT and tax), run it for two years, build up some no claims and then get the car whose picture hangs on your bedroom wall. You won't be too broken hearted or financially worse off it is damaged or totalled.
Once you get a good few years no claims, your premiums will tumble.
I now insure 3 cars for £510.00 fully comp with a £100 excess, unlimited mileage and no they aren't worthless basket cases.
I think a parent would have to be very generous to put you on their insurance as in the event of a claim it would be a blot on their insurance record as the policyholder. Anyway most policies are named drivers only and those under 21/25 who want to drive will have special terms imposed on them. But that has always been the way. It was the same when I was 17yrs an age ago.
Perhaps you could put up posters appealing for anyone who witnessed the damage to your car to come forward? It's worth a try. If the damage was as substantial as you imply someone must have seen it? The other vehicle must have been damaged as well? It is an offence for some one to drive off from the scene of an accident without giving their details to anyone who legitimately requires them. If you can't trace the offending vehicle and driver then unfortunately that is one of life's cruel lessons. **** happens as they say.
Drive carefully.
Andy