Darin Cosgrove's special Pontiac Firefly can get up to ... Darin Cosgrove's special Pontiac Firefly can get up to 64-mpg. Attaching a boat tail to the car greatly improves its aerodynamics, transforming it into a very unique and fuel efficient vehicle. (Darin Cosgrove / Ecomodder.com)

"If you want attention, this is how to do it," says Darin Cosgrove of his unique, high-performance car. Sporting a distinctive boat tail for aerodynamic enhancement, Cosgrove's Pontiac Firefly, a Canadian-market version of the Geo Metro, does not slip by unnoticed. A left turn from hot-rodding, Cosgrove's quest for maximum efficiency is better described as Eco-Modding. Indeed, he's put his money where his mouth is and co-founded the Ecomodder.com web community, an outpost for like-minded enthusiasts, many of whom played a part in collectively brainstorming the car's new bodywork.

Other than the sheer enjoyment of sinking your teeth into a technical challenge, why would someone want to do something like this?

"It's a different kind of motorsport," enthuses Cosgrove, "this is an activity you can do that's a lot more affordable and legal, you know, you're not pushing the speed limit boundaries, you're pushing the efficiency boundaries."

As for the car and its four-foot extension? "The goal of a low drag vehicle is to leave as little disturbed air behind you as possible so the more the rear of the vehicle tapers down, the smaller the disturbed wake is behind the vehicle," explains Cosgrove. The design brief required any modification be easily installed, small enough to fit in the vehicle when not in use, and of course, lightweight.

The tail is the finishing touch to a vehicle-wide program for Cosgrove, who admits, "The stumbling block is the way it looks."

Drivers seeking less attention can opt out of the visible modifications, though. Taller gearing and a different camshaft are nuts-and-bolts modifications that are entirely invisible. Rear-wheel spats and smooth wheel covers will clean up the airflow on virtually any automobile, and production hybrids like the Honda Insight sport similar setups right from the factory. A smooth belly pan underneath the car cleans up airflow below.

"[This is] something [automakers] can do without getting into that sort of sticky area of consumer acceptance," Cosgrove explains. "Because, it doesn't change the way the car looks but it still knocks a couple of points off the coefficient of drag."

Serious Performance

With the prototype tail installed, the Firefly squeezed out 64 miles per gallon during testing. That kind of efficiency would pay for the materials in weeks, instead of the years (or never) that some supposedly green vehicles take for a return on investment. A more finished version of the body modification will be constructed once the snow melts, following the proof-of-concept version's design.

"I started with four aluminum struts that are physically attached to the car," Cosgrove elaborates, "it's sort of a combination frame and monocoque construction, it's got internal bulkheads."

While the car isn't as outr?s the rolling-fuselage Aptera, the prototype cardboard-and-duct-tape appendage is enough to pique curiosity. 

"I've met more neighbors," Cosgrove recounts of the building process, "in the couple of days that I spent on the driveway building the tail and then testing it, I had people stopping at the end of the driveway to get out of their cars and say 'Okay you have to tell me what you're doing...' so it was really actually kind of neat."

Not everyone loves it, though. Apparently, the horsepower-modder's chase for volumetric efficiency is fine, but go after aerodynamic efficiency at your own peril.

"I've been doing it long enough that it doesn't really bug me," Darin says of his critics, but clearly ecomodding isn't fully understood by all. "They just go ballistic when they see somebody doing something 'weird' to a car to this extent." In his own defense, Cosgrove isn't some car-hating weenie with his nose buried in research. "I've spent more than a few dollars myself on the race track in high performance driving schools and it is a hoot. It's a fantastic way if you can afford it and you have no compunctions about burning the resources to spend an afternoon on the racetrack...it's a blast."

High performance automobiles are typically sprinters, not marathon champs and fuel economy doesn't often cross the mind of many hot rodders until it's time to fill the tank. Exceptional efficiency is a different interpretation of high performance that only gets attention when the price of fuel spikes. "When fuel prices go up, the number of people who are interested in it for strictly economic reasons just goes through the roof," says Cosgrove. "The amount of traffic we had in the forum last summer when gas prices in the states were up around four bucks...it was huge."

Press coverage of the Firefly's tapered tail has assured eco-enthusiasts that they're not alone. "It does definitely feed on itself. The more people that find out about it, the more who are interested in it," says Cosgrove of the result of the media attention he's gotten for the Firefly, Ecomodder, and victorious participation in fuel economy challenges. The enthusiasm has already spawned at least one commercial endeavor from a forum member, much the same way lakebed racers looking for more punch out of their Flatheads pushed the development of the stalwart high performance brands we have today.

Though he doesn't see a tail in kit form for Joe Public's minivan, Cosgrove says "Aerodynamic add ons for the transportation industry are already showing up on the roads, you've seen them yourself, the lower skirting on transport trailers on highways;" can boat tails be far behind? "The answer's definitely yes," says Cosgrove, "you can see studies where they're doing boat tail additions, not extreme down to a tip but partial boat tailing of the rear of transport trailers."

For regular car enthusiasts, there's no shortage of appearance and hop-up parts out there in the aftermarket, so high efficiency is likely to be just one more niche to serve. In the end, it's all applied science, so some will apply the same research and practical techniques to go very fast, while others will use the means to an end of going very far, instead.

Read More:

- How To Drive For 100 MPG
- 100+ MPG Cars: Six Cars You'll Drive In The Future
- The Thinking Man's Future Green Car

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