I can tell you a bit about autoglym lifeshine/permagard protection as my brother in law has a chemical company and he bottles and sells it for Mercedes, and the Inchcape chain. The claims that it offers lifelong protection are nonsense. It's basically a numbers game for permagard, because the number of sales generated by making that claim outweighs the payout to people who go back and challenge it.
Yes, it does put on a protective layer, but this does erode over time, and gives no more protection than a good wax and polish. To keep the protection it needs to be redone.
The interior protection is worth having, as it is in effect, a scotchguard like stain repellent. It won't provide a 'waterproof membrane', but it will stop stains soaking into the fibres of the cloth or grain of the leather. so if you tackle a spill quick enough, you'll be fine and dandy.
Apparently there is German product (can't remember it's name) which does offer a hard impermeable shell for paint protection, which has been tested on the hulls of boats to keep them barnacle free, and does not come off. It's in very limited supply at the moment because its a new product, but apparently it is mega bucks. The problem is of course, permagard claim the same thing for their product, offer a lifetime guarantee and is considerably cheaper. If you knew no better, which would you have?.............
ive seen them in the showroom with it on and it looks pretty good 
