Daft question I know but my car says Cayenne Turbo on the back so I have always thought that is what it is but whenever I go online (HPI, insurance etc) it says its a Turbo S, it also says Turbo S on the V5 document.
Someone in Wales DVLA has pressed too many buttons on your V5. HPI, Insurance etc take info from DVLA so get DVLA to correct it otherwise if you get stopped by Police they may thing car is moody!