I just finished my first 700 mile tank! 701.6 to be exact. It took 12.056 gallons to fill it back up, 58.2 MPG. It's like the efficient switch suddenly turned on or something. My previous high was 52.85 MPG on a full tank. Does the HCH tend to break in "suddenly" and start to be significantly more efficient? It was right about 17,000 miles when I saw a jump in efficiency. I don't think I've been driving differently.

 

Congrats on your long tank - and more importantly great FE!

Maybe the weather warmed up some on this tank - a little heat (and no wind/rain) can do wonders for FE.

Or, maybe your last fill was really higher FE and this one was really lower FE

 

It does break in, but I think Sparty is right--temps are warmer and it's easier to get great mileage. Still, nice job on the 700 mile tank! How many miles did you drive on "no bars" of gas?

 

Also, it could be your gas station just switched from winter gas to summer gas which can make a big difference. When I drive from San Jose to Tucson for the holidays each year, I noticed that I usually see a 4-5 mpg bump (it's not much warmer than San Jose in the winter) when I run on AZ gas instead of CA gas. I believe AZ keeps the same formulation all year, unlike CA.

-dan

 

The weather has been a little warmer, and I keep a spreadsheet that clearly shows a difference between mild weather and extremely hot/cold weather. This tank is much higher than I have previously gotten in similar weather conditions.

I drove about 80 miles on no bars, and planned on putting 12.4 gallons back into it, but the display was reading lower than actual fuel economy, so I could have gone further. The most I have ever put into the tank is 12.4 gallons, and I stop at the second click. I don't "top off" and fill up the filler neck.

I considered this, but I'm pretty sure they made the switch a few tanks ago, when I saw a consistent jump from "winter" mileage to "spring" mileage.

 

good job!

 

Congratulations on the mileage, but I think there is no honour in testing the limits of a tank of fuel. What is the cost of getting yourself stranded? You have likely taken that into consideration and minimized the risk; I'm not accusing you of anything, but showing my concern over the principle of driving methods. Had you increased your refill frequency and averaged the results over the trip I'm sure it would be about the same.

I sometimes get asked, "How far do you go on a tank?" And my response is usually, "What does it matter? Tank sizes are variable and therefore they don't represent a meaningful comparison of fuel efficiency."

 

for RockMonkey ... CONGRATS! seems to me that's quite a milestone ... pun intended! but, as others have suggested, do be careful about running out! 701.7 would mean almost nothing if you wind up needing a tow to the nearest station.

incidentally ... a few years ago, i drove 543 miles on a tank in the car we have; a 1997 Dodge Stratus with 2.4L / 4-speed automatic. it took a bit more than 14.5 gallons to fill up the 16-gallon tank, and our mpg for that stretch was a bit over 37.

for spinner ... oh, i LOVE that response of yours ... not only for the reason you give, but also for this one: it depends on how many gallons one uses before deciding to "fill up" again.

 

It matters for the convenience factor of having to fill up less. Trust me, in the winter in Chicago I am very glad in February that I am getting 500 miles a tank.

 

I just had a 701.4 mile tank, too! After a couple years with my car, I know how far I can go after the fuel light goes on or the fuel gauge bars are all gone. I've never ran out of gas and my commute is mostly the same, so I don't feel there's any risk. I just think it's awesome to have a car that can go so far between fill ups. With the price of gas these days, mentioning the mileage I'm getting or the miles between fill ups to those who are still driving their gas-guzzling vehicles (all by themselves - not carpooling!) has gotten a few of them to think twice about what they're driving. One person bought a HCHII and another bought a Toyota Corolla, each of them more than doubling their previous MPG's.
So when someone asks me how far I can go on a tank of gas, I gladly tell them but also let them know my MPG as well. IMHO it DOES MATTER!