Today after fill-up it read 550 miles (after fill-up it usually showsą520); after driving about 180 miles it is showing 435 miles left. It is clearly miscalculating the remaining range. That never happened before. I tried restarting the car, opening and closing gas tank cap; still reads the same. Anybody experienced the same problem?

 

I suppose you already know that the approximate range displayed is based on recent fuel usage. It calculates range based on you not changing the conditions in it's recent memory. I don't know how accurate or how far back it calculates to arrive at the displayed figure.

 

I did not change my driving habits. It is clearly overestimating the range.
It started overestimating the range after my last fill-up

 

wow im averaging about 12-13mpg on my CS, i dont think ive broke 300 miles on a tank yet, but i always drive it in sport, auto start on/off disabled and fill up right when or just before the light turns on.

 

Gjmattos is right. The PCM will give you a different answer based upon your current driving style. When I am doing highway driving I get about 525-550 miles to a tank and about 400 or so in the city. Nothing is wrong, just the way the system works. You may not think you changed the way you are driving but even a subtle change in speed or altitude can cause a change.

 

Coming back from a trip last week the display read 34 MPG after 250 miles. I stopped to fill up when I pulled off interstate near my house and the display read 780 mi range when I turned the key. I know I would not see that if it were city driving for 250 miles. The range is based upon your recent fuel consumption. Today after driving 80 miles back home it posted 37.4 MPG, crazy good.