The tank is 12.3 gallons. You can physically pump more into it because the filler neck holds an additional quantity.

Another possibility is that the gas pumps are rigged to display a higher volume of gasoline than is actually pumped. But I believe that's rare.

A lot of hybrid owners concern themselves with small variances in tank-to-tank mpg readouts. The only readout that matters is a cumulative one.

I left "trip B" untouched since I bought my HCH last year. After 23,000 miles, it reads just over 47 mpg. That's the figure I cite whenever someone asks me about miles per gallon.

The trip meter recycles every 10,000 miles, so it may not be completely accurate. But it's as close as anyone needs. Try it.
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