New guy here

[deano]

300... that all. Is that all around town ?
I used to get 300 from the v6 models

[jasonmayall]

All around town, so it's never going to be as good as motorway driving but it's definitely using too much I think, but by how much I'm not sure.

[deano]

my 300 was a mix of motorway and town.
motorway 60/40 town.

[dollysprint]

After you have checked the thermostat I would then go on to replace the coolant temperature sensor and possibly the gauge temperature sender if the gauge reading still plays up. 20 to the gallon is well rich if you are staying off boost, should be more like 25-27 around town as long as your town dont involve 30 min traffic jams at every road junction. 65mph motorway driving should see closer to 40mpg on a good "T" series.
Thermostat, cts and gauge sender are all on the stat housing and so all can be done at the same time and that rules out the whole assembly then should further investigation be warranted.

Dave

[rovercoup]

Spot on advice Dave as I had the same with the coupe and once I had replaced the aforementioned items the car drives much better and has a stable temp gauge reading at about 8 O'clock.