I commute 50 miles each way to work. 90+% of my mileage is (very hilly) highway. I got my 2012 Prius C2 on the last day of Jan 2013. As of today I have 20 fill ups, 6281 miles in 2 months (included a nearly 2000 mile vacation trip). I just filled up today and I have a full tank, so I will get another 350+ miles out of this tank for sure. I *STILL* have not spent $500 on gas YET! I'm at $490 (link to my fuelly acct below). That's flat out amazing to me. I was spending well over $500 a MONTH for just my gas. now less than $250 a month. well that justifies my car payment right there! and my wife, who also has a 2012 C2 but does not track her miles/fuel on fuelly, gets even better mileage than I do b/c she's 90% city driving. Just wait til summer and 4+ months of 100+ temps and I bet I get even better gas mileage! I know this is nothing new, but it's just amazing to me how little I am spending on gas, even tho I drive more than most.
After watching me drive Entu for a few months, being a passenger and seeing me pull 80-90 mpg on 10 mile trips, my mother-in-law traded her 6-month-old Rav4 for a new C2. She went from 18 mpg and 50 bucks a week on gas down to... hardly 50 a month in fuel.