Despite common belief speed is not really connected to MPG. The Revolutions Per Minute (RPM) of your car's engine is what really matters.
If your car has a Tachometer watch your RPM's, keeping them low will use less fuel. Depending on the gearing of your transmission is what determines how fast you travel at a certain RPM.
by TikiTantrum on August 08 2008
this tip works for 67% of voting Fuelly members.