View Single Post
Old 05-10-2016, 10:04 AM   #26 (permalink)
Batman Junior
MetroMPG's Avatar
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,459

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

MPGiata - '90 Mazda Miata
90 day: 55.97 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 70.75 mpg (US)

Appliance car - '14 Mitsubishi Mirage ES (base)
90 day: 67.41 mpg (US)
Thanks: 3,997
Thanked 6,889 Times in 3,574 Posts
Hi, Steve

Originally Posted by Manualhybrid View Post
empirically (without a scan-gauge), I found that a slightly higher speed than the lowest possible RPM speed in this condition produced a better result--45 mph or so yielded better fuel economy.
I wonder if what you saw is the difference between optimal (flat road, constant speed) testing conditions vs. "real world" driving where it sometimes makes more sense to cruise a bit faster than the lowest speed at which top gear/lockup engages just to avoid automatic downshifts on hills, slight acceleration, etc.

24.9 mph--which must occur prior to torque lock-up--is an even better efficiency speed!
I've seen this in a few vehicles -- but only ones with automatic transmissions. Even though it isn't in top gear, the aero load is reduced enough at 40 km/h / 25 mph that it comes out ahead. If you could manually shift up to the next gear, the "dip" seen in the next 2 data points would disappear.

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

has launched a forum for the efficient new Mitsubishi Mirage - fuel efficiency info for Geo Metro owners - electric car conversion on a beer budget
  Reply With Quote