I’ve recently purchased a 1973 Volvo wagon. The fuel gauge goes from F to 1/2 to R (at that point the range color goes from green to red) and then a the bottom it’s either a O or a 0. What does the R stand for? "Really gotta get gas? I don’t know. I’ve been playing it safe and not letting reach the R. As my grandfather used to say, “It cost just as much to keep a half a tank as it does to drain it and fill it.”
“R” stands for “reserve.” In olden days, some cars had a hand operated valve for the fuel tank. In the normal position, you’d run out of gas while there was still a gallon or so in reserve at the bottom of the tank. You’d then turn the valve to the reserve position to access that, and look for a filling station. As far as I know, this system was in lieu of having a fuel gauge.
And the “0” is a zero, for empty.
Survey says:
Gary T nailed it. (as usual)
My father’s first VW Beetle had that feature. His second Beetle had a proper gauge, but it was not working 