• Question: In a car we are driving to Dublin it usually takes 1hour travelling at 100kn per hour however it would take a lot longer if travelling at 80km per hour but which speed I journey would take less diesel

    Asked by DLANG to Cathal, Dave, Karen, Bobs, Roisin on 6 Mar 2017.
    • Photo: Karen Barrett

      Karen Barrett answered on 6 Mar 2017:

      In this case, I will assume that it is not city driving, and that it is a long journey without stops. It is what the car industry calls smooth driving.

      My answer is that driving at 80km/h will use less diesel.

      Usually, when cars are driven at 100km/h they are less efficient at using their fuel. This means that the engine burns more fuel to make the car travel at 100km/h that it does at 80km/h.

      There is research that has shown that a reduction in speed, while driving without stops and at a constant speed at all times, can produce fuel savings of 12% in a diesel car.

      While the journey may take a little longer driving at 80km/h it will use less fuel because the car and engine will run more economically.

Comments