cbCA

Hi all - I have a 2011 ct and for a good part of the first year the mileage range display read upwards of 400 miles on a full tank. About 3 months ago I took a 3-day road trip and was blasting the AC for much of the time. I also had bike racks on the roof of the car w/ 2 bikes. Since then the full tank mileage range has been closer to 350, and after about 75 miles or so I'm down to a quarter tank on the fuel gage. Not sure what happened.... is this a computer thing? Anyone else had anything like this?

Thanks,
C