In his endless quest to squeeze every possible mile from a gallon of gasoline, our friend Darin Cosgrove has given his econobox a homemade boat tail and boosted his fuel economy to 64 mpg.
Cosgrove, the founder of the hypermiling site Ecomodder.com, used cardboard, aluminum and duct tape to extend the back end of his 1998 Pontiac Firefly – as the Geo Metro is known in Canada – by 4.5 feet. The mod took him about 14 hours to do, and the results are impressive enough that he's planning a sturdier version made of more durable materials.
"I've driven with the tail on for about 300 km in total, mostly at highway speeds up to 100 km/h," Cosgrove told us. "I didn't notice any change in handling. The only effect on driving is I have to watch out for rubberneckers in other cars. Seriously."
We believe it.
The tail joins the rear wheel skirts, bellypan and other mods he's made to boost aerodynamic efficiency. The result isn't much to look at, but it boosted Cosgrove's fuel efficiency by 15.1 percent at 90 km/hr (56 mph).
"That 15 percent is just from the tail: multiple bi-directional averaged runs at exactly 90 km/h on a straight and level road, absent other traffic," Cosgrove said. "The tail was removed and reinstalled during the test so the 'A-B-A' comparisons could be made in identical conditions."
Cosgrove figures all of the mods cut the car's drag coefficient from 0.34 to 0.23. That's an unofficial, back-of-the-envelope figure he estimated using a pretty cool online calculator posted over at Ecomodder.com.
By the way, 64 mpg is actually a walk in the park for Cosgrove, who used the “pulse and glide” technique to get an astounding 99.7 mpg during the Green Grand Prix in May. And as wild as the Firefly might look with a tail, it's nothing compared to Mike Turner's wild Aerocivic, a Honda Civic that gets 95 mpg.
POST UPDATED 5 p.m. Eastern to include more details and photos.
Photos, video: Darin Cosgrove. Get a full rundown on the mod and the testing here.
https://www.youtube.com/watch?v=1sQFtd-bTfw
