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Old 06-24-2020, 09:19 PM   #14 (permalink)
EcoModding Lurker
Join Date: Jun 2010
Location: Edinburg, VA
Posts: 74

The Little Car - '00 Chevrolet Metro
90 day: 91.08 mpg (US)

The Big Car - '94 Chevrolet Caprice Wagon
90 day: 44.9 mpg (US)
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Originally Posted by MetroMPG View Post
Can you describe your & her primary hypermiling techniques?

There's one additional factor that wasn't on my list of "mods" that I'll mention before I do: we run ethanol-free gas 100% of the time. We live in a very rural area, but it turns out that there's a small convenience store that sells ethanol-free gas only one mile from our house. They have ethanol-free because we're also just a few miles from a lake. The ethanol free gas they sell is 93 octane "premium," though. Their "regular" gas has 10% ethanol. So, because of this I have the ignition timing advanced a bit more than I could if we used regular gas, since premium is less likely to exhibit spark knock. It's not a huge factor, but it does help some.

The techniques we use are straight out of the "100+ hypermiling tips" on this site. There are a bunch of little things we do that all add up, but the three big ones are (1) reduced speed, (2) constant P&G with EOC, and (3) minimizing braking as much as possible.

We live in a rural area, so there's typically not a lot of traffic and/or stops. Most of our driving is on rural roads and highways with a speed limit of 55 MPH. Even when I travel for work (which, before the epidemic hit, I did regularly), I tend to avoid the interstate so that I can keep my speed down (and avoid the stress and traffic). I usually pulse from 35-45 or 40-50 MPH, unless the traffic or speed limit dictates otherwise. If I need to go faster because of traffic or someone following me who can't pass, I'll pulse from 45-55. On longer trips, then, my average speed is usually ~45 MPH. I pretty much never do steady state driving, though--it's always P&G (and my wife's the same way, too).

We live in southwest Virginia, which is pretty hilly/mountainous. This has advantages and disadvantages. The advantage is that the hills make for "natural" P&G--we pulse uphill, and glide down. The disadvantage is that there are some hills with stops at the bottom we can't avoid, and some hills that are so long and steep that you have to brake going down them (no matter how slowly you crest) to avoid speeding. So, route planning to avoid these stops and hills is pretty crucial.

Almost all of my best tanks have been on trips with flatter terrain--usually either to eastern VA or to OH/IN. My best ever tank happened last April on a trip to Norfolk, VA and back. Practically the entire trip was on a state highway (Route 58) that's flat, has few stops, and a speed limit of 55 MPH. The weather was warm and clear for most of the trip. I pulsed my usual 35-45 or 40-50 MPH the entire way there and back, and averaged 98.8 MPG (so close to 100!!).

So, the hills in our area are definitely a challenge, but one that can (mostly) be managed with careful planning and attentiveness to the terrain. I'm sure that our winters are much milder than they are in Canada, though!

There is one thing that I've discovered, unique to the Metro, that may or may not be helpful to you (I'm guessing you've probably figured this out already, but I'll share it in case there are others who haven't). The Metro seems to go into open loop fairly easily (i.e., with not too much throttle opening relative to the RPM) and when it does, open loop is MUCH richer than closed loop. So, I've found that making sure the engine stays in closed loop (while keeping as much load as possible) makes a pretty significant difference in fuel economy with this car.

On my ScanGauge, two of my four "gauges" are open/closed loop, and MAP. When the engine is on (again, practically always "pulsing"), I aim to keep the MAP reading at 90 kPa or more (max load) while staying in closed loop. There's usually only a very narrow range of throttle opening where this is possible, but if you keep it there, it pays large dividends over giving it too much throttle and going into (excessively rich) open loop. Eventually, you start to "feel" where that "sweet spot" is, and don't have to rely on the ScanGauge as much to keep it there.

On the Caprice wagon, I was able to tune the ECU to stay out of open loop until at least 80% TPS opening, so on that car it's super easy to stay in high load and closed loop (while still having power enrichment if you really need it). I wish I could do the same with the Metro, but unfortunately, the Metro ECU can't be reflashed.

Anyway...that's the long and short of our driving style. My wife drives pretty much just like I do, except she (self-admittedly) isn't always as hyper-focused as I am.


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The Following 4 Users Say Thank You to funkhoss For This Useful Post:
Gasoline Fumes (06-25-2020), MetroMPG (06-24-2020), oldtamiyaphile (12-20-2020), Silent Blood (07-15-2020)