Hypermiling attempt #2, 92.4 mpg over 14.9 miles

Attempt numbah two:

92.4 "real" mpg from Scangauge



With the warmer weather and recent talk of hypermiling on PriusChat, I couldn't help but go out (even on an otherwise busy day!) for a little under an hour of fuel economy practice. With my limited time, the only place nearby was up the big hill in my town, on some back roads with low speed limits and relatively sparse traffic. The biggest problem was the route: I could only drive for about 5 minutes before coming to the end of the road, and would have to do a 180 to go the other way. There was also a stop sign in the middle. This means I had to stop every 2.5 minutes.

I didn't glean too much from this run, other than some useful ideas regarding pulsing and gliding on slight hills. I actually tend to get better mileage in the middle of one of my commutes - I can usually get over 100 mpg for fifteen minutes straight if I don't get stopped at too many lights. This run was interesting for me since I was trying to use lower speeds for a change, not more than 35 mph, sometimes lower, and also seeing what's possible while stopping so much.

While the best results on flat ground historically tend to be between about 18-20 mph on the low end and around 34-35 mph on the high end, I found slowing to 18 mph on a hill and then accelerating to be a bad idea. You're still trying to accelerate with a gas engine going at relatively high RPM but low torque with the slow speeds. This results in a longer burn time to reach the desired speed.

The simple solution is - well, there isn't one, but at least in the particular terrain I was on, I did try to go a little faster, keep momentum, and make sure I came into the hills with some speed, which I would sort "artificially" maintain with a very short pulse to not destroy momentum while cresting at the top. Using a small amount of EV while heading into the hill (not more than 10 amps, so it's less than warp stealth use) will help keep it moving a tad more than jumping straight to gas, but without a huge drain on the battery.

I don't have specific segment mpgs, but the 5 minute segments approaching the hills with more speed, air resistance be damned, easily yielded better mileage visually than the other bars.

Finishing up the stop and go section of the trip, I had about 88 mpg on the Scangauge. I tried an interesting, circuitous, and mostly downhill route home to get it up to 92 :-)

Meanwhile, still searching for an appropriate road for pulsing and gliding near my home - without stop signs or lights!

Hypermiling attempt #1, 80.9 mpg over 37 miles

Attempt numéro un:

80.9 over 37 miles, and within that trip, about 92.46 mpg over 32.5



The titillating details

So it was a lovely Friday morning, and although I had some things to do, I couldn't ignore the mid-40s to 50°F temps outside, the warmest I've had yet since owning the car - so I headed out for a some first hypermiling attempts.

There is a rare stretch of a mile in my town with a. no traffic lights, at least until the end of the mile, and b. two-lanes so that people could pass me. I wanted to try this out first.

I attempted to accelerate to speed (40 mph) at about 25 mpg average over .2 miles, and I was able to just about hit the numbers (probably .25 or .3 miles). I let up on the accelerator for the engine-off glide, and let the car go. There were some humps in the road a little too big to ignore, so I used minimal electric energy to keep the glide going. At the end of the mile (a little before...when I was crawling to a stop and there was a convenient road to turn into), I had about 89 mpg. I then turned the opposite direction, rinsed and repeated, and came out with 98 mpg for both of those miles combined.

The problem was, if I wanted to do this repeatedly to get 100 mpg over many miles, each time it would necessitate turning around 180° and starting from a dead stop, and obviously that's not ideal for mileage. I also felt I had to use too much EV (electric mode), which would wear down the battery too much after a couple passes. If I tried over and over, I would imagine on one of the attempts the gas engine simply wouldn't shut down, as it would want to recharge the battery pack.

So I tried something else...

I've been wanting to scout out some back roads in two nearby towns to see what I could do with hypermiling and no traffic. The particular towns in question have a wonderfully low population density, and not too much traffic to go with it. The one problem is that all roads are one-lane over there. I don't know the roads at all, topographically speaking, so it was a bit of challenge.

They worked out pretty nicely, but not great. There were lots of lightly rolling hills, and without knowing where they were, I would sometimes get lucky, but sometimes not, having to sustain the engine on for much longer than one would want trying to get 100 mpg.

At the end of the stretch of road there was an awkward turn around (by the end, since I'm in Rhode Island, I mean when I had to stop to avoid driving into the ocean) which lowered the average quite a bit, but I think I it should be possible in those towns in the future to have a go at 100 mpg for at least a half hour. I'll have to go at a time with no traffic, since around 10-11am when I was there, although mostly clear, I did have to either speed up when I didn't want to or slow with my hazard lights to let others pass.

Now, as I headed over there on the highway, pretty much all gradually uphill, I travelled about 2.3 miles at, I would guess, 30-35 mpg average from a 0-50 mph acceleration. I didn't reset the mileage display, so those numbers are figured into these 37 miles. On the way back, more down hill, I would guess a 50 mpg average on the highway portion. There's another couple sustained 20 mpg uphills I had to do on the way home which I won't even take out to keep the numbers conservative. So if we take out the gas consumed on the highway miles (.111 gallons) and subtracted those miles as well (4.5 or so), you get 32.5 miles travelled on .3515 gallons consumed, or 92.46 mpg. So conservatively, good to see Wentworth can get at least 90 mpg over about 32.5 miles!