I have a 2008 Sonata with the 4 Cyl 2.4L engine and 31k miles. I have owned it for about a month now and so far so good.

One thing I have noticed - it takes about 3 miles of driving before the coolant reaches its maximum temperature. (just below half on the coolant gauge) On my old 1996 Acura it would only take about 1.5 miles before it reached its max. I live New Mexico and lately our high temperature is 40 and the low around 20 - it seems to take 3 miles anywhere in this temperature range.

This seems a bit slow to me - have other owners noticed the same lag time for the coolant to reach max temp? Or is my coolant thermostat misbehaving?

 

I have the V6 not the I4 but that sounds about right to me.

 

It all has to do with the physics of heat transfer. During warm-up on a cool/cold day, you most likely have the heater/defroster on which actually takes some BTU's away from the engine on warm-up. Other factors come into play involving the design of the cooling system, thermostat, even the marks on the temperature gauge.

There are two things you can do just to make sure.... change the thermostat, and change the coolant to exactly a 50/50 mix. That'll be as good as it gets when warming-up.

Personally, I wouldn't worry about it. Just give the car an extra moment on engine start.