Sorry me again.
my sharan is very slow to warm up on the temp guage. i drove for 40mins today before any heat came out of the vents.  the temp fluctuates from 50 to 60 to 90 on a journey. am i right in assuming this is the thermostat?

in addition to this when slowed to a stop in say traffic the temp drops and then fumes come into the cabin.  im assuming this is the aux heater glow plug that needs replacing. Any other suggestions?

i love this car its new to us but my its testing my patience already :)

I have a similar thing on my Alhamb, I'm told it's because the engine is extremely efficient and produces very little waste heat. The aux heater never works tho so I wouldn't worry about that.

Check the temperature of the radiator compared to the hoses - or check both sides of the thermostat. If both seem to be the same temperature, then the thermostat isn't working properly (might be stuck, broken, got something caught in it or missing completely)

Also if the engine is running cool, it may not be running as well as it should, which could account for the smell when standing as well, no idea on booster heater on the mk3 but if its anything like the earlier models it won't be coming on until it gets colder. They also generally have a seperate exhaust but then the mk1/2 is a completely different vehicle so could be different.

Sounds very much like the thermostat is stuck open if you get no heat after 40 minutes of driving, especially when weather isn't even that cold yet.

we had a 64 reg Sharan for 3 years that had a Webasto as opposed to Eberspächer heater and was mounted behind engine and exhaust came out by o/s/f wheel arch, am sure it was 10 degrees before it would switch on.