If you are talking about an aftermarket, molded-to-fit dashcap, I have installed 2 of these, one in my old 76 350SE, and one in my current 85 380SE. The first one was stuck down with a double sided tape supplied with it. Lousy adhesion. The second, I used silicone, liberally.

These install easily without the need to remove the original dash, and can probably can be removed simply by carefully prying up from the edges and 'peeling' it off. If you are worried about tearing the vinyl on the underneath original dash, don't. Just fill with a bit of silicone and the new dashcap will cover it up anyway.

Now, if you mean the original dash vinyl, as MTI says, forget it, it's permanently molded to the foam underlay and aluminum shell. You want to leave it in place anyway to install the aftermarket dashcap.

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1986 560SL
2002 Toyota Camry
1993 Lexus