Mopar Muscle Association UK

That's a tough one, my first guess would be Armor All, but perhaps Frosts may have a solution (ahem!) on their web site. 8)

What about autoglyms leather care products that you can get from Halfords. I bought some for my volvo and it can be used on vinyl so I've been using it on my charger too.
Seems to make the vinyl a bit more supple.

I've tried to scan the autoglym bottle but my scanner refuses to work so I'll type some of what it says on the back.

Leather care cream also cleans and protects textured vinyl and other plastic surfaces inside and out, imparting an enriched natural finish. For a silicone-free finish on dash panels and facias apply sparingly, buff and allow to dry.

Perhaps I'm reading too much into it but when I've used it on vinyl the cream seems to get absorbed into the vinyl same as the leather. My mate has used it on his boat and reckons it worked a treat. There must be something made especially for vinyl though.

Did you see this on Frost? Could be just what you need as it says it reconditions vinyl.
http://www.frost.co.uk/item_Detail.asp?productID=8036

hmm baby oil , i love the smell , but it must be the leading brand .
on a more serious note , try a horse shop , one that sells sadles and things, my other half had a stuff for her synthetic saddle that softens and polishes it , mabe it will work on car vinyl in the same way. i will ask her if she can remember what it was,

Steve, I wouldn`t put any neat solvents on the vinyl, it`s likely to remove any oils left in the vinyl. You need something with plastisols in, or silicones.

I just cleaned 30 years worth of grime from the off white seats of the Charger with Nitro-cellulose thinner. Took the gunge off a treat, but if you rub it too hard the vinyl goes sticky so I gues it is melting it. Need less to say I went a bit carefully and got the worst off. The seats will still need something on them to soften them up a bit though.

well, talking of removing grime, I recently cleaned my white vinyl top with neat household Flash. It sure removed the muck, with the use of a scrubbing brush. Don`t get it on the paintwork though.

My previous comment of not using a solvent was meant as a word of warning - use it, but don`t leave it on the surface for long. I had to use paint stripper on the vinyl roof to remove some stubborn marks, but it was straight on and wiped off. Even then I could tell it was attacking the vinyl. It`s now had copious amounts of vinyl polish applied.