Auto MPG: Fuel-Efficiency Shifts, Outliers, and Data Gaps

auto_mpg · model-year trends, origin splits, cylinder patterns, anomaly vehicles, and horsepower caveats

Average Fleet MPG
USA Dip, 1972 → 1973
USA Rebound in 1974
Missing Horsepower Rows
Story framing
How fuel efficiency changed

    Exceptions
    Cars that break the usual rules

    Average MPG by model year and origin
    The USA line is emphasized to surface the 1972–1973 dip before the 1974 rebound.
    Engine-size split: average MPG by year and cylinders
    Switch origin to compare how cylinder mix and efficiency changed together; blank cells mean that combination is absent rather than zero.
    Weight usually hurts MPG — except for the 1981 Oldsmobile Cutlass LS
    Marker size encodes cylinders. The highlighted point sits far above the overall weight-to-MPG fit.
    Horsepower usually hurts MPG — except for the 1980 Datsun 280-ZX
    The horsepower scatter excludes the six rows where horsepower is missing, so the fit is not distorted by blanks.
    The six missing-horsepower vehicles still matter in MPG summaries
    These rows remain valid for year and origin trends, but horsepower-based analysis should exclude or impute them deliberately.
    Exception register: two anomaly vehicles plus the missing-horsepower rows
    Flag Vehicle Year Origin Cyl Horsepower Weight MPG