Confused about mileage

Dear Lazyweb,

Why does my Chrysler Sebring (3,400 lb, 2.4 liter V-6) get 27 MPG while an Aprilia Atlantic 500 scooter (425 lb, 0.46 liter 4 stroke) get only 45 MPG? If weight is any indication, shouldn’t it get more like 200 MPG?

2 Comments

  1. Andrew says:

    Gas milage is a function of both the effeciency of an engine and the weight of the vehicle (amonst other things). Your 6 cylinder v6 engine will with 6 firings per rotation of the crank shaft provide much smother power than a single cylinder can. This means the engine is acutally running slower in theory all things being made equal it will run 6X slower than an single cylinder engine.

    A better indication might be to look at the power to weight ratio of the vehicle as a whole.

    Then you get into gearing of the vehicles a car will have gears designed to get it up to speed where then engine runs slow allowing one to cruise along at highway speeds without an annoying and expensive engine screaming along at 100,000 RPM.

    Basically gas milage is a much more complicated formlua to work out than just weight = x therefore MPG = Y. Any aspect of the vehicle’s design from the drive train to the aerodynamic profile can drasically affect it.

    Cheers, Andrew

  2. Joe Cecil says:

    I thought that a 4-cycle engine fired every other revolution. Therefore, a V-6 would fire only 3 cylinders per revolution.

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