Trying to beat my previous MPG record

Updated with final results below. . .
=====================

I've always tracked my gas mileage on all my vehicles and taken an interest in getting the best mileage I could whenever possible. My 10 month old Prius is no exception. In fact, it's become quite fun to see just how big a mpg number I can squeeze out of it. I can only do serious record attempts when the timing is right. I don't consider it a good record attempt "for me" unless I've driven at least 400 miles on that tank. Unscheduled road trips and/or hauling 4 people just kills a record attempt but this week is looking good.

Normally, I'd just post a pic in the MPG stats thread. I had a request to show the HSI images along the way as the mileage increases during this attempt, thus a separate thread. I know others have done better but this is just for my enjoyment and so you can watch if you want to.

I always hand calculate the actual MPG with each fill up so we will not know the final MPG until the end. Hopefully it will be higher than my current personal best from June 4th, 2010 of 66.6 mpg (hand calculated) over 410.0 miles. (HSI showed 69.5 on that tank) So far it's looking good but "stuff" happens.

Tire pressure is 37 front and 35 back. Temps have been 81° in the morning to 96° afternoon with humidity ranging 40% - 80%. No A/C so I usually stop for the day when I melt around 1pm. I have at least 117 miles of the first 315 at speeds between 45 - 55. The terrain has a variation between high and low of 450 feet (rolling hills with flat areas)

Note, I used the same pump to fill up before and at the end of the test. Both times, I stopped filing with the first pump handle click off. I did not top off the first or last tank.

So far:

6-21-2010, mile 93, 75.3 mpg
6-21-2010, mile 158, 74.6 mpg
6-22-2010, mile 203, 77.4 mpg
6-23-2010, mile 315, 78.9 mpg

EDIT: Drum roll . . . . the final result . . .

6-24-2010, mile 417.8, 80.7 mpg HSI and 76.4 mpg actual
(417.8 miles on 5.471 gallons of 100% (no ethanol) gasoline)

My new personal record is 76.4 mpg. The test is completed.

 

You're getting there quickly. I haven't been able to try a 700 mile tank because I can't get that much time to try it without road trips messing it up.

 

Feels good though doesn't it?

 

Wait until you catch yourself holding your breath trying to squeeze that extra bit of mpg.

I've never done that though . . .

 

Thanks, but the fat lady hasn't sang yet. It seems that 80° is the enabling point for extraordinary mpg. That's just a gut feeling, no facts to back it up. It's gotten real hot a month early here.

 

Normally I would use the incredibly efficient A/C, but during this high mpg attempt it's just my driver's window down most of the time and a white shirt to reflect the sun. Our UV has been 10 - 11 for the last week.

I do have a slight tint from the dealer (80% I think). It does help. It's been very windy lately, 10 - 25 mph so I try to keep aerodynamics in mind regarding the windows being down. If I remember right, the Mythbuster guys said 40 mph or lower didn't add much drag having the windows down. Problem is if you're driving into a 25 mph headwind at 40 mph you have a 65 mph drag. In that case I just turn on the vent with one or two of the back windows cracked about 3 inches down.

I've learned that when you get above ~65 mpg average on the HSI display, it doesn't take much to bring it down and it takes a lot longer to get it back up there. Every little thing makes a difference. You know, like when those BMW's pull up next to you and you just gotta hit the PWR button to teach them some respect, yo.

For example, if I could do this all in one day, it would be a lot easier. Why? At 70+ mpg average, you loose almost 1 full mpg every morning just getting the engine up to stage 4 operating temperature. Only then can you start working to bring it back up. Starting out with a cold engine even with an 80° 7am morning is a real consideration to overcome daily.

It's a fun challenge. I'm anxious to see what Wednesday brings.

 

For high mileage attempts/competitions it probably would help. I have a 1 mile long 200ft climb either direction I go when I get onto the main road from my house. At 80° outside temp, it takes about a mile to reach 164° coolant temp. This morning I only lost 0.4 mpg during that warmup. I also had 315 miles done so it would take more to reduce the average.

My final numbers are in. I'm uploading pics now.

 

It sounds like you're getting there just fine. One thing to note is I never interfere with the traffic flow. I have some fairly expansive neighborhood streets and some rural county roads that I did all of this test on.

LOL, no it's pretty much up and down with long flats. These rural asphalt farm roads are not smooth. Tons of potholes and washboard. Don't be ashamed. I'm only competing against myself.

56.5 mpg is wonderful in my book.Good job!

 

Thanks, the heat is a killer for sure. It's 11:30am and I'm done for the day.

I want to try it again with the A/C just to see what it can do.

 

My new personal record (actual) is 76.4 mpg!

I'm surprised and amazed at the same time. The HSI showed 80.7 mpg so it wasn't as far off as I thought it would be.

I drove 417.8 miles on 5.471 gallons of 100% (no ethanol) gasoline. My DTE still showed 212 miles available but I just learned this morning that I have go do a family thing tomorrow and it's not in town so I cut it short.

Note, I used the same pump to fill up before and at the end of the test. Both times, I stopped filing with the first pump handle click off. I did not top off the first or last tank. That would skew the numbers.

I had fun doing this. I was very careful not to interfere with traffic and selected my driving areas carefully.



Not that there are any doubters but here's a copy of my gas receipt with the parts you don't need to know removed. (That's my ODO reading written at the top.)