Abstract: Apparatus and method for determining vehicular distance per fuel unit, such as the miles per gallon or liter of fuel consumed in driving a car. The vehicle has a fuel gage, and when stopped on, or operating on level road, a reference mark is made where the fuel gage pointer is then located and the odometer mileage reading is recorded. Vehicle operation is continued and when convenient, fuel is then added to the fuel tank to cause the pointer to show a greater quantity of fuel in the tank than is shown by the reference mark. The vehicle is then driven until the fuel gage pointer again returns to the reference mark, and the total distance traversed is also determined. With the knowledge of the amount of fuel consumed and the total distance traversed, the distance traversed per unit of fuel can be calculated.

Abstract: A reference index is provided for dial type instruments and includes an indicator selectively positioned on the face of the instrument for operation in either of two functional modes. The reference index includes a mounting pivot which is adapted to be secured to the face of the instrument and carries a mounting block that is relatively rotatable about a pivot axis projecting from the face of the instrument dial. Carried by the mounting block is an indicator having an elongated arm which has one end pivoted in the mounting block for relative rotational movement in a plane parallel to the face of the instrument, or perpendicular to the pivot axis. Formed with the outer end of the arm are first and second reference tabs which are adapted to overlie the circular indicia ring of the instrument. The two tabs are perpendicularly disposed to each other and project transversely to the longitudinal axis of the arm.