Engine Temperature

I presume you are talking about water temperature, for wich there is a gauge in the instrument cluster. The needle needs to be at 90 degrees and not 1mm left or right when engine is warmed up. I think that your thermostat is faulty, but to ensure that it is, you need to connect your car to a VAG and see. I changed the thermostat on my S3 a year and a half ago, and when it was faulty my temp. gauge was showing around 86 degrees and this wasn't a big problem,but 75 is too low, and you should solve this problem A.S.A.P. The thermostat at the dealers was something around 45-50£ without labour, you should also change the antifreeze while at it, I'd go with the new long-life G13, you need 2 cans of it, 2x1,5L and that shouldn't be more then 20£ ..

no thats not normal to be showing lower than 90 , however it is normal for the engine thermostats to need replacing in these engines.

my old bora used to be the same and the garage said "some temp gauges just read differently"

it'd only hit 90 if I'd been in it a while and stuck in traffic, as soon as I was at 30mph or more it'd drop just below empty

thermostat off ebay for about £7, changed it myself, lost a load of coolant cos I'm a clutz, topped it up tho and took it for a drive, sat perfectly at 90c

if its in an easy enough location to get at and change it, the thermostat really isn't a costly job, even if you don't go cheapo ebay