mine isnt a highline, but it has all the OE's the highline has (apart from leather which i didnt want anyway) climate control, recaro seats, tints, sun roof etc. etc.. nope, some highlines were in 5 door. (binliner has one for a start)
My oil temp hardly goes above 104 degrees. but i might get one all the same just to make things run cooler as it runs hot in general, if you are replacing ur stat then get a nu-speed one
I generally hit 30's when im motorway driving... when im driving around it's always between 20 and 23 MPG now ive had it mapped and the valve timing has been adjusted.
most RR will have diagnostic s/w that will generally read any errors stored on the ECU. Not too sure of any places in Kent. I have family who live nr folkstone, I'll ask them!