Posted Tuesday, October 3/06 in General

Harry Stevinson was decades ahead of his time. In 1933 at the tender age of 17, he put his self-taught mechanical & design talents to work fabricating a streamlined one-off car that was both faster and more efficient than the Model T Ford it was based on.

I learned about Harry and his car from his son, Tom, who lives near the same town I live in. Tom and I sail together in the local sailboat races, and the topic of his dad's Model T came up one day in the marina parking lot when he commented on some modification I had made to the Blackfly.

What emerged was a fascinating story along similar lines as the aero-modified Metro XFi - only this story took place 60 years earlier...

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Posted Saturday, September 9/06 in Mods & Tests

One of the biggest aerodynamic problems with the majority of hatchback-shaped vehicles (like my Blackfly) is the size of the trailing wake. The large reduced pressure zone acting on the rear end can account for up to 1/3 of total drag.

That said, a hatchback configuration isn't automatically an aerodynamic death sentence. On the contrary, three of the most slippery production cars available in recent years were hatchbacks: the 2nd generation 2004- Toyota Prius (Cd .26), 1999-06 Honda Insight (Cd .25), and 1999-05 Audi A2 (Cd .25).

But these cars are exceptions to the rule. So what do you do if you're stuck with a conventional more or less van-shaped hatch? Just grin and bear the aerodynamic shame of it? No way! Get out the cardboard and duct tape, and go to work fixing what the stylists messed up!

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Posted Thursday, August 31/06 in Mods & Tests

Mirror, mirror on the door -
Is your airflow good or poor?

Sorry. I won't do that again. But that is indeed the topic of this installment of what sadly appears to be becoming a once-monthly update at MetroMPG. (I will try harder in September - it's not for lack of subject matter, believe me.)

My desire to find concrete information about the effect of side mirrors and fuel economy was piqued from seeing the number of high-efficiency concept cars that substitute video cameras for side mirrors. Why? Is it just for the techno bling factor? Or are there real gains to be made by rethinking side & rear vision?

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Posted Wednesday, August 2/06 in Mods & Tests

The fact that you're reading articles on a fuel economy web site says you're probably already aware that speed kills ... mpg. Resisting the urge to drive fast is one of the easiest and most effective methods for seeing big savings.

We've all seen stats from NRCan and the EPA about how much more fuel is burned as speed rises: Driving at 120 km/h instead of 100 uses about 20% more fuel (NRCan); observing highway speed limits can save 7-23% (EPA).

Those are serious numbers. But reading a stat is one thing, and seeing it laid out graphically is a real eye-opener. So I set out to collect some hard evidence for the Blackfly: a graph of speed vs. fuel consumption.

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Posted Friday, July 14/06 in Suzukiclone info

Apologies to my reader (to borrow a joke from Click and Clack) for the long delay since my last post. I spent most of June on a trip, travelling about 1400 kilometers on a 100 ton diesel hybrid. But I'm back now, catching up on a variety of tasks, and have a serious backlog of interesting things to talk about.

Let's start with this radically modified-for-fuel-economy 1989 Geo Metro XFi.

Apparently, owning one of the most fuel-efficient cars ever sold in the U.S. wasn't enough for Doug Heffron. So in 1993, motivated in part by his daily 50 mile commute, he transformed it in his garage into this amazing 2-passenger highway commuter car capable of 75 mpg (US) (3.1 L/100 km; 90 Imperial mpg). That's a whopping 29% higher than its original EPA highway rating.

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Posted Wednesday, May 31/06 in Driving efficiently

As I mentioned in my previous record tank entry, I used to do a fair amount of engine-off coasting in my Honda Accord. The main reason I abandoned the technique in the Firefly was because it messed up the ScanGauge, which would go to sleep when I killed the ignition (and skew its fuel economy information while it missed counting distance travelled).

As soon as I learned that a kill switch that bypassed the key kept the ScanGauge active with the engine off, I immediately set out to run a test to find out what I'd been missing.

Turns out, I'd been missing a lot.

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Posted Tuesday, April 25/06 in Driving efficiently

Two records were broken lately: oil hit $75 US a barrel, and I squeezed 60.7 mpg (US) from my last tank of gas - a personal best.

(For those of you more fluent in other units, that's 72.9 imperial mpg, or 3.9 L/100 km.)

You'd be forgiven for thinking that the return to high gas prices and my recent fuel economy performance are related - but they're just a happy coincidence. In fact, for most of this tank - actually, before the latest spike in gas prices - I had been test driving a new driving technique. Well, really it's an old technique that I had stopped using and have now returned to with open arms... and great results.

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Posted Wednesday, April 5/06 in General

The further you sink into MPG nerdity, the sooner it will become clear that you need to know how accurate your odometer is. Why is it important? I'm glad you asked!

It's important simply because an inaccurate odometer will throw off your mileage calculations. Maybe your fuel economy is actually worse than your odometer has led you to believe... or maybe it's better! Maybe you switched to different wheels or tires (with a slightly different circumference). Or maybe all this time your odometer has been out of whack straight from the factory, and you just didn't know it.

A 2% error on a 50 MPG vehicle = 1 MPG off. And a 2% error (or worse) isn't uncommon. The fact is, you'll never know if you don't check it out.

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Posted Monday, March 27/06 in General

Revolutionary feedback ...

Since posting my RPM vs. MPG experiment, I've heard back from a couple of people. Some good points were raised, so I've added their comments to the end of that page.

Jump to Showdown: testing RPM vs. MPG at a fixed speed and scroll to the bottom of the page for the new stuff.

More miscellany after the jump...

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Posted Monday, March 13/06 in Mods & Tests

If you row your own gears (as most fuel economy nerds do), here's a mini-experiment that should be of interest.

I recently did a test run that nicely illustrates the fuel efficiency "costs" of reciprocating mass, accessory drag, and internal engine & transaxle friction at varying engine RPM.

If you ever doubted the economy driving tip that says you should be in the highest practical gear at the lowest possible cruising speed, doubt no more.

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