The Prius has an 11 gallon gas tank (give or take - I think the exact specs say 11.9, but the gas bladder is collapsible and the general consensus is that a fill-up will take you just over 10 gallons, which has been our experience), which is psychologically rewarding in that when I fill up my tank I don't generally pay over $40. The better mileage we get, the less we have to stop and fill up. So we generally have to fill up about once every 10 - 12 days.
For a long while after we bought the Prius, our gas mileage hovered somewhere between 43 and 47 MPG, depending on the type of driving we did. The hybrid motor seems to do best in city conditions and stop-and-go traffic, since it can use the batteries more. Therefore, we typically get better mileage when driving in the city than we do on the highway.
Over the past few months, however, we've been trying to drive smarter - coast to stop lights and down hills, let the terrain help propel the vehicle rather than the gas pedal and, hardest of all - we've tried to slow down on the highway.
Driving 55 MPG on the highway saves gas. Period. Some really stupid people out there probably still "reason" that if they drive 70, they'll get to their destination faster, and won't be on the road as long, so they'll save gas, right? Wrong-o. A 2005 article in the San Francisco Chronicle puts it this way:
For every mile per hour faster than 55 mph, fuel economy drops by about 1 percent, said Jason Mark, clean vehicles program director for the Union of Concerned Scientists. The drop-off increases at a greater rate after 65 mph. The faster you go, the faster the fuel goes.
[Mark] figures that a commuter making a 30-mile drive to work at 65 mph instead of 75 mph would save about 30 cents in fuel costs per day -- or $150 a year -- and spend just 3 1/2 minutes more daily on the road.
But driving 55 has it's drawbacks. It takes longer to get places, for one. Then there's the people who get right up on your bumper like they want to drive right over you. Or the assholes in the SUVs and trucks who gun it past to make some sort of point. I laugh at the gunners - you just wasted money to try to piss me off. It didn't work. You happy now?
Since we used to drive about 65-70, we've been trying to pull that back to 58-60. And I think it's working.
We got 50.4 MPG on our last tank of gas - almost 500 miles - while running the air conditioner non-stop because it was so fracking hot outside.
There's always the talk about how the Prius isn't a good value because the price you pay for it vs. the savings in gas doesn't even out. I hate math, so I'm not going to run any numbers. What I do know is that I hate to put gas in the car, and I really hate putting over $80 worth in every 5-7 days (like we have to do with our Jeep Cherokee, which is why it gets driven about once a month). Forty dollars every 10-12 days vs. eighty dollars every 5-7 days seems like a pretty good deal to me. I also love the keyless entry and start, the navigation system, the back-up camera, and all the other bells and whistles that I smile about every day.
I'm not trying to get you to rush out and buy a Prius by any means. But I was so happy with our last tank of gas that I just had to tell someone. Who better than you? :)