2006 in review: mods vs. technique. And the winner is...
 

Driving technique won over mods by a pretty wide margin: 37.5% vs. 28.0%. Though you'll have to buy into my "comparison" method to believe it. It's pretty inexact (to say the least...)

Tallying just the mods ...

5.2% tranny swap
http://www.metrompg.com/posts/tranny-swap.htm

10.3% alternator optional
http://www.metrompg.com/posts/alternator-optional.htm

2.3% kardboard kammback
http://www.metrompg.com/posts/boat-tail-prototype.htm

2.3% mirrors
http://www.metrompg.com/posts/mirrors.htm

5.7% grille block & rear wheel skirts
http://www.metrompg.com/posts/grille...ing-part-2.htm

2.2% undertray

= 28% total theoretical improvement over base from measured mechanical/aero mods

I'll be the first to admit this tally is flawed on several levels: 1) the weather conditions weren't the same for all tests; 2) the speed wasn't exactly the same for all tests (but close to 55 mph); 3) the effects of individually tested aero mods can't simply be summed because their effects interact with one another ... the car is probably more or less than 28% better with all the mods in place. But the car was never driven with all of them in place at one time and then without.

Driving technique ...

To do this comparison, I looked at 3 tanks in Firefly #1 which were predominantly city driving. When I was using that car, I wasn't employing coasting of any form, or P&G/codfishing, and there were none of the mods listed above.

Firefly #1, 3-tank tally: 1474 km, 83% city driving ... 5.2 L/100 km / 54.0 mpg (Imp) / 45.0 mpg (US)

Blackfly, 3-tank tally: 1724 km, 83% city driving ... 3.3L/100 km / 86.5 mpg (Imp) / 72.0 mpg (US)

If you do the math, that actually works out to a 60.2% improvement for the Blackfly.

The biggest flaws in this comparison are: 1) it assumes the "base" cars are identical (which they were on paper, but probably weren't in reality) ; 2) the Blackfly has some mechanical & aero mods on it that the other car
didn't have. Based on the values in the mods list though, we can correct for these mods:

- 5.2% transmission advantage
- 10.3% alternator advantage
- 1.2% aeromods advantage (calculated based on avg. city speed of 25 mph vs 55 mph for the tests)
- 6.0% rolling resistance (this is a WAG - the Blackfly has LRR tires and higher pressures than the first Firefly had)

------
-22.7% total deductions (this is actually a liberal estimate, because the Blackfly was not running alternator-less, nor with all aero mods, and the taller tranny was only in place for 2 of the 3 tanks)

= 37.5% estimated difference due to driving technique

Only a piece of the puzzle
 

Technique is great, but what if you want to just hop in the vehicle and drive reasonably?

I prefer to rely on mods more. Besides, if someone else drives the car, those fuel saving devices are in place.

Best of all, I suppose, is to start with a great platform.

I'll admit, I had the biggest jump with extreme technique, but it wears on more than just the longevity of vehicle components. I'll still engine-off coast now and then -- but not as often, for example :o

RH77

Ahhh, but the cost to change techniques is priceless.:p. You don't have to be completely radical to show a huge increase if FE with techniques alone.

People will have different approaches to saving gas, and that's to be expected.

But there's no question that adjusting the nut behind the wheel is the easiest & cheapest approach. It also has the benefit of being portable - you can take it to every vehicle you drive. Can't do that with mods.

True
 

True, very true. Let me play the Devil's Advocate here. But how then to promote the site? Mods imply wrenching (espcially with the logo). Perhaps both points-of-view could be represented and let the user decide? Same for extreme technique vs. emissions, etc...

But yep, Z has the point of them being Absolutely Free!!!

-R

You can mod your car and/or your driving.

Both approaches will be embraced - it's all good here.

That's what I was envisioning -- good stuff.

-R

Both are useful. I'm just fixated on the idea that the power actually required to move a person and groceries, rain or shine, at highway speeds (ar or near) is at least an order of magnitude less than the current average mode of transport.

I'm also frustrated at the limits of my car and don't like the constraints imposed by the automotive industry. I know that what I'd like (and what the world needs) can be designed and only has to be designed once, then mass produced. It might also be possible that retrofitting is an option - the only problem is that the cars out there are all different, so there is no one size fits all solution - you can only target low hanging fruit, where the modifications are easy and significant.

Modifying the car serves several purposes:
1. Further improvements to FE after adjusting the nut behind the wheel has approached diminishing returns.
2. Proof of concept that load on engine can be further reduced at highway speeds (aero).
3. A starting point for reducing fuel consumption given that smaller load, or switching powerplants.

A logical endpoint is the VW 1 litre car, or something like a heavily faired Honda Cub.

Modifying the driver is always going to have a great return - barring some sort of miraculous battery technology that is near 100% efficient to charge and discharge, of appropriate weight, etc.

Unfortunately, carmakers are in the "transportainment" industry, not the transportation industry.

As long as vehicles are marketed and purchased as fashion statements, we're going to get foolish un-aerodynamic designs like the Volt for a vehicle that's (going to be) laughably held up as an icon of efficiency in North American transportation options.

And you're also right - even if it triples the average fuel economy of the US fleet, the volt is 10x more vehicle than we need.

This guy is moving in the right direction with the BugE.

I say mods support and assist better technique.
The two work together for a synergistic effect.

Many of my mods decrease rolling resistance or air drag; some reduce engine load (e-fan). Without reducing rr and drag, P&G was nearly worthless. It wouldn't coast. Now with hard tires and some aero mods it will coast nearly anywhere, though still loses some speed of course.

Also if you consider adding SG or SuperMid to be a mod, then that also supports improved technique.