If it's the same as my E46 then it does seem to be the case. I thought my mpg was a little low, so I checked the temp. An 8 mile journey this evening showed just 70 something degrees, until at a standstill when it climbed to 87 very briefly.

I asked the garage I bought the car from if the stats were OK beforehand, and was assured they were, so I will send them an email tomorrow to see how they want to proceed...