Have you deleted/renamed the glide.dll and glide2x.dll in the Carmageddon folder?
Yes I did, I renamed every glide .dll and .ovl folder.
However I have now resolved the issue, it turns out the windows 95 patch just didn't like my AMD graphics card. I switched to the intel integrated graphics (I'm on a laptop) and the game runs perfectly now at the correct FPS- not at half speed like it was doing with the AMD. A rookie mistake perhaps but i'm at sea when it comes to PC gaming! Driving in slow motion was throwing me off!
This is the first time I have played carmageddon 1/2 I can see why it has the cult following, very fun destruction Derby-type game (But with much more character). :)
The Win95 patch doesn't work for everyone, but unless running it in DOSBox is too intensive for your system then I can't see why you wouldn't run it in DOSBox and make use of nglide for a higher screen resolution to get sharper looking graphics.
Looking at your shortcut, being as the software shortcut referenced two conf files, shouldn't the hardware (3DFX) one also reference two conf files? i.e.
"C:\GOG Games\Carmageddon\DOSBOX\dosbox.exe" -conf "..\dosboxCARMA3dfx.conf" -conf "..\dosboxCARMA_single.conf" -noconsole -c exit
Without that second one (dosboxCARMA_single.conf) you won't have any autoexec commands, so DOSBox would load, set up to the settings for 3DFX, then quit as no application was started within DOSBox, which sounds like what you were experiencing.