Could a coolant temperature sensor cause poor gas mileage? The reason I'm asking is because my wife's car took a lot longer to warm up this morning. It was about 52 degrees this morning. And the gauge on the dash didn't get half way between the 1/4 and 1/2 marks. And I travel about 30 miles to get to work. And I also notice the average mpg went down on highway to 20.4 when it was warm outside it would say about 27 to 30. We have been chasing the poor mpg for a couple of months now. Everything has been changed from basic tune-up to new o2 sensors and new converter. Running ngk iridium plugs and 8mm wires. Any help would be appreciated. And we are getting between 10 to 15 city driving
