mine is also like this it takes 5-10 minutes for the engine to even go 1/4 warm.
but once on the move after going on the high way and sitting at the lights it reaches 1/4 to nearly half and goes back down to 1/4 while driving at 80Kms+
If im only doing urban driving it always stays on cold (50kms p/h regular street limit)
I do have a feeling its pretty accurate.. my engine bay has alot of space becuase of no power steering, no aircon all that woosy girly stuff is out also my water splash guards are out so theres alot of airflow..
You shouldn't really complain though just give it a good warm up like i do. me and my friends who have 4AG's warm it up for 5/10minutes at the start of the day while having a quick brekkie or getting ready. It takes about 5-10minutes depending on weather for the cold idle to settle down anyway.
And as for effiency maybe on fuel if you boot it alot while its still cold.
As long as it doesnt over heat and you keep an eye on your radiator fluid. you wont wreck your engine or headgasket that will keep you and both your 4AG happy