My manual says 16 gal for my car a 2007 2.2 LT. That seems about right but I have only put in 12.3 gal. at the most. Just got my car with 29000 miles on it and put 4000 miles on it in 28 days. I never let it go below 3/4 tank and I usually cruise at 80 on the interstate.
Yes, I was! The total mileage I can travel on a tank of gas is higher in the HHR than in my old minivan. I almost forgot I needed to fill up until the LOW FUEL message appeared on the DIC. Fortunately, the next exit on the interstate did have a gas station or I would have been walking!