Quite sure the name 'Foxy', as an affecionate term for the VW in Pakistan, was an evolution of the word 'Volkswagen' - and doesn't refer to the adjective, which means 'sexy, seductive'
Commonly-used colloquials for other VWs in Pakistan include :
'Foxy dubba' - The VW Bus (Type 2)
'Fokker wala Foxy dubba' - Split screen VW bus (the hippy bus)
'Foxy jeep' - The VW trekker/type 181
Also heard the VW being refered to as 'daddu' i.e. frog, in rural areas.