Subcategories:
You can see the full category hierarchy on the Category Map.
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| purity | |||
| 83% | BRAKE | Brings to Rest All Kinetic Energy | 
                Eric Bridgstock | 
| 100% | CLUTCH | Control Lever Under The Car's Heater | 
                Eric Bridgstock | 
| 100% | DOOR | Don't Open On Route | 
                Steve Keate, referring to a car door. | 
| 100% | ENGINE | Emits Noxious Gases Into Noisy Environment | 
                Eric Bridgstock | 
| 100% | GAS PEDAL | Gains Automotive Speed. Probably Encourages Driving At Limit. | 
                Eric Bridgstock | 
| 100% | HEADLAMP | Helps Espy Any Danger Lying Across My Path | 
                Tony McCoy O'Grady | 
| 100% | INDICATOR | I'm Nearly Directionless, I Could Abruptly Turn - Or Reverse! | 
                Tony McCoy O'Grady | 
| 100% | SPEEDOMETER | System Pacing Each Engine's Distance Or Miles, Except Times Equipment Reverses | 
                Rico Leffanta | 
| 100% | WHEEL | Wonderfully Helpful, Enabling Easy Locomotion | 
                Tony McCoy O'Grady | 
| 100% | WINDSCREEN | Where Insects Normally Die. Stops Crud Reaching Eyes, Ears & Nose | 
                Eric Bridgstock | 
| 100% | TYRE | Tube, Yet Rotates Evenly | 
                Eric Bridgstock |