car:    Automobile
mpg:  [ Mileage, mi/gal ]
cyl:  [ Number of Cylinders, [ four: 4, six: 6, eight: 8 ]]
disp: [ Displacement, in^3 ]
hp:   [ Gross Horsepower, hp ]
drat:   Rear Axle Ratio
wt:   [ Weight, klb ]
qsec: [ Quarter-mile Time, sec ]
vs:   [ Engine, [ V-shaped: 0, Straight: 1 ]]
am:   [ Transmission, [ Automatic: 0, Manual: 1 ]]
gear: [ Number of Forward Gears, [ 3-speed: 3, 4-speed: 4, 5-speed: 5 ]]
carb: [ Number of Carburetors, [ 1, 2, 3, 4, 6, 8 ]]
