View Single Post
Old 07-13-2015, 11:15 AM   #36 (permalink)
MetroMPG
Batman Junior
 
MetroMPG's Avatar
 
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,534

Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 54.46 mpg (US)

Appliance car Mirage - '14 Mitsubishi Mirage ES (base)
90 day: 57.73 mpg (US)
Thanks: 4,082
Thanked 6,979 Times in 3,614 Posts
Finally got the RE92's on the Firefly/Metro



Happy coasting indeed!

After 4 years, I finally got around to sticking the "winning" Bridgestone Potenza RE92's on the Firefly. (Because the car that was wearing them -- the ForkenSwift electric car, top photo this thread -- was retired last year).

Despite the presumably worse aero of the slightly wider tires (165 vs. 155) plus air-blender alloy wheels vs. the car's stock, smooth-ish 13 inch wheel covers, the car got much better mileage on a round trip (back roads) to a cottage:
  • 76.8 mpg US (Goodyear Invicta) round trip
  • 82.5 mpg US (RE92) round trip
Notable: that was with a 3.2 km/h (2 mph) higher average speed on the RE92 trip. (Similar weather & traffic conditions ... mostly deserted back roads driving, 87 km / 54 miles round trip.)

(Note: the RE92's have a ~1.4% smaller circumference than the Goodyears. I didn't apply this correction to the speed/distance figures here. Even corrected, the MPG % difference is much larger than the measurement error.)

Most of this was driving with load (DWL) on rolling terrain, but I definitely made use of the obviously better coasting ability of the RE92's when approaching most turns & stops (engine off).

Of course, in fairly typical ecomodder fashion, I changed more than one variable: the car also has a brand new air dam on it. So I can't say how much of this improvement is from the tires alone. It seems unlikely it's all from lower rolling resistance. (But I plan on A-B-A'ing the air dam...)
Attached Thumbnails
Click image for larger version

Name:	$$$$suzuki-alloys-on-RE92.jpg
Views:	669
Size:	54.9 KB
ID:	18289  
__________________
Project MPGiata! Mods for getting 50+ MPG from a 1990 Miata
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: 70 MPG in my ecomodded, dirt cheap, 3-cylinder Mirage.
Ecodriving test: Manual vs. automatic transmission MPG showdown



EcoModder
has launched a forum for the efficient new Mitsubishi Mirage
www.MetroMPG.com - fuel efficiency info for Geo Metro owners
www.ForkenSwift.com - electric car conversion on a beer budget
  Reply With Quote
The Following 2 Users Say Thank You to MetroMPG For This Useful Post:
BabyDiesel (07-16-2015), niky (07-14-2015)