If there was a part p for cars, you would not be allowed to fit a car stereo, an alarm, or do any electric work at all. The car itself would probably be classed a special location (after all, its outside and exposed to the rain).
There is the MOT, which is quite cheap, compared to how much it would cost to get extensive electrical work checked/approved etc. The mot covers quite a lot of points, and still stays a reasonable price.
But the law does not stop you from doing any work, you can do what you want to your car, as long as it passes its mot.
Out of interest (as its years since I last had a car) do MOT stations check the eproms in cars to make sure they have not been modifed by boy racers?
Do they they check *all* they electrics (to ensure a dodgy self installed alarm or sound system etc wont kill the cars electrics when its driving down the motorway... Do they use things like xray, and high zoom microscopes to check the metal work for fatique? Or do they still just poke it with a screwdriver and if it does not go through its structurally fine?
A DIYer who is doing a job above his or her capabilities is likely to do the job anyway regardless of part p (and with part p they may be less likely to ask for help, in case someone shops them......)
They may also be less likely to point out to new buyers any work that they did themselves, not wanting to get done due to part P. Without part P they would have no fears of mentioning any diy work that was done, so at least the buyer is kept informed of what has been done, and where...
