Rust-belters: check your rear brakes/wheels for drag!
I'm replacing the worn-out brakes on the new-to-me Fancy Metro, and noticed when I got the rear wheels up in the air, the drums did not spin freely. There was quite a bit of drag. (And, no, the parking brake was not on. )
Drag = bad for MPG!
Turns out it was from rust building up along both margins of the braking surface, high enough to start touching the edges of the pads.
They cleaned up quickly with a wire wheel on the grinder.
They now spin effortlessly & quietly, like the almost-perpetual-motion devices that drum brakes should be.
Good for another 10-20 MPG, I figure.
View my fuel log 2014 Mirage SE 1.2 manual: 56.0 mpg (US) ... 23.8 km/L ... 4.2 L/100 km ... 67.2 mpg (Imp)