Top 10 hypermilers AVG spd over 50mph

I have never seen over 45 mph average on my car, despite using it *very* sparingly for city driving.
Bob wilson posted a chart that shows mpg vs mph using cruise control on level roads, without AC.

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I noticed your avatar. I assume it is a political statement of some kind, so I thought you might like to see a chart of average national petrol prices in the US for the last 8 years, in case you are under some delusion that prices are set by a president except for a few weeks (see if you can pick out the time) by playing with the petroleum reserve:

 

To the OP: I actually do remember the gas price when Busch took office. C'mon we are not that dumb or gullible.

I went ahead and made myself a new avatar.

 

Joshua

You know when the avg +50mph then the Prius top speed is somewere closer to +70 mph and going that fast really makes the MPG go waaaay down ....However, it just so happens that I have tanks with an AVG speeds greater than 50 mph recorded on my mileage log for hyperdrive 1 on cleanmpg.com (2010 Toyota Prius III). These tanks were part of an interstate +85% superhighway trip last April. My excuse to go that fast was that I had two funeral to attend to one on Friday in St Louis Missouri for my favorite Uncle Jimmy and one on Sunday in Washington, DC for the father of some dear friends I drove on Thursday 4/12/2012 from DC to to St Louis and then drove on Saturday on 4/14/2012 from St Louis to DC. I had to cover about 800 mile in one day (not counting rest periods it takes about 12 hours. My tire pressure was set a tad low 38 psi/36 psi because I was worried about traction at high speed in the rain. While Thursday 12th was sunny , it was raining all day on Saturday April 14th and the roads were really crowded making it very difficult to hypermile. My highway hypermiling skill are not very good so I wouldn't used them as anything to aspire to . However, if misery loves company - it might make you feel better that at very high speeds even a Prius' MPG will drop ...


4/12/12 479.3 miles 9.267 gallons 51.7 mpg MFD avg 55 mph
top speed is 80 mph, 66-70 mph using cc, sunny

4/14/12 442.1 miles 9.428 gallons 46.9 mpg MFD avg 54 mph
top speed is 80 mph, 70-77 mph using cc, raining all day

4/14/12 415.1 miles 9.317 gallons 44.5 mpg MFD avg 62 mph
top speed 82 mph, 70-80 mph using cc, raining all day

before this road trip my overall MPG was 61 mpg
after this road trip my overall MPG dropped to 59 mpg
Ever since that road trip I've been working on bringing my MPG back up to 61 mpg

 

As a general rule hypermilers don't have average speeds over 50mph because as Walter stated, that would mean lots of drive time at 70mph. That's too fast for good numbers so hypermilers don't do that. Especially not when trying to set records for themselves. FWIW my average speed is usually 43-45mph for a tank in the 60-66mpg range. My 90% freeway commute is done at 60mph cruising speed.

 

I travel 80/90% highway - or more. My typical cruising speed on the highway is 60 or 65 mph. One problem is I live in an area with a lot of significant hills so it is rare that I "cruise" for more than a mile or so. Most of the time I am fluctuating between 45-50 mph on the ups and 65-70 on the downs.

With my new Gen 3 I seem to be getting around 54-58 mpg in this warm weather. High speed driving kills fuel economy in my experience. My gut feeling is that speed control is the number one factor in fuel economy.

I should also say that I do not consider myself to be a hypermiler. I do pay attention most of the time and when I do I get somewhat better fuel economy. Sometimes with my old 08 I would just set the cruise control at 65 and frankly I did pretty good that way as well.

Also, my average speed is generally quite a bit less than 50 mph. This is key to good fuel economy in IMHO. If you are averaging over 50mph and getting over 50mpg I'd say you are doing fine.

 

In hilly terrain at highway speeds, the hypermiling technique Driving with Load (DWL) is the only FE safe driving option. DWL is essentially accelerating downhill, decelerating uphill, and coasting at the top of the hill -- which sounds like what rpg21 is doing. DWL is easier to do when there isn't much traffic on the highway - a busy and congested highway makes doing DWL problematic at best and impossible at other times. Time shifting your trip to a non-rush hour time can help with this matter. Other ways to coax FE from a Prius is to decrease the top speed to less than 55 mph and increasing your tire pressure to about 5 to 7 psi more than the recommended door jam specs. Unfortunately, if one restricted the Prius's top speed to about 55 mph then Prius MFD AVG spd will register signficantly less than 50 mph --so it would not meet the primary qualification of the OP. WRT to the OP primary qualification of a MFD Avg Speed of 50 mph - the minumum sustained (median) driving speed needs to be somewhere around 68 mph if atleast 90% of all driving is done on the superhighway because each acceleration and deceleration period/phase recorded by the Prius main computer will pull the MFD Avg Speed downward. Driving mostly at the median speed of 68 mph in very good weather, with no elevation/gravitational advantage, a non-drafting Prius should get on a Prius MFD avg=50 mph and about 54 mpg and calculated at the pump I would expect that the Prius should achieve about 48 mpg. Not too shabby but not +70 mpg. If the Prius is driven in the rain or on rough pavement (e.g. grooved/rough road surfaces - created before a repavement of the road) you can minus 2 to 5 mpg off your fuel efficiency for that trip.
BTW: Using 15" tires, my Prius speedometer reads about 1 mph faster than what a radar sensor, speed trap camera, or my GPS unit registers. For example, if my Prius speedometer reads 81 mph my Garmin Nuvi GPS unit reads 80 mph. If my Prius speedometer reads 27 mph, the trailer based traffic radar speed sign says my Prius is going at 26 mph. At very high speeds like 68 mph, a vehicle with a smaller frontal surface and lower aerodynamic coefficient like the 1st generation Honda Insight has a fuel efficiency advantage over larger vehicles like the 2nd/3rd gen Prius.