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MetroMPG · 11-05-2013, 11:55 AM

Highest gear, lowest reasonable road speed.

People often mistake the "sweet spot" on the BSFC (Brake Specific Fuel Consumption) map as meaning that's where they should always try to operate the engine.

Not so. As RedDevil explains, that's where you want to operate the engine when moderate/heavy load is required (ie. when accelerating or climbing a steep grade).

But not when cruising at light load. Go for the highest gear/lowest RPM.

11-05-2013, 11:55 AM	#3 (permalink)
MetroMPG Batman Junior 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	Highest gear, lowest reasonable road speed. People often mistake the "sweet spot" on the BSFC (Brake Specific Fuel Consumption) map as meaning that's where they should always try to operate the engine. Not so. As RedDevil explains, that's where you want to operate the engine when moderate/heavy load is required (ie. when accelerating or climbing a steep grade). But not when cruising at light load. Go for the highest gear/lowest RPM. __________________ 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