Automotive Dictionary

We know mechanics can speak their own language. That’s why we’ve tried to de-mystify some of the more unusual terminology to ensure you’re in control of your vehicle.



The electromagnetic unit of charge, equal to ten coulombs.

The action of two gear teeth making contact.

After market:
An automotive replacement part provided by a company other than the original vehicle manufacturer.

All-wheel drive (AWD):
Sometimes confused with four-wheel drive (4WD). This drive system features four, full-time active drive wheels that reduce slippage and provide greater control of the vehicle. Unlike 4WD, AWD is an on-road system and is not designed for off-road use. AWD does not need to be activated by the driver, it is operational all the time.

Ambient air:
Air outside the vehicle passenger compartment.Anti-lock brake system (ABS):Wheels are equipped with speed sensors. When a sensor detects that a wheel is decelerating too rapidly the EHCU (electro-hydraulic control unit) is activated. The EHCU modulates the brake pressure across the appropriate brake lines so as to prevent wheel lockup and help the vehicle maintain directional stability in potentially hazardous braking situations.

Aspect ratio:
The ratio between the width and height of the tyre. Tyres with lower aspect ratios (usually found on sports models), provide superior handling but a harsher ride.

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Elvio is a seasoned Motor Mechanic with 25 years experience in the automotive industry. Well-known for asking the most obvious questions and his bizarre obsession with Datsuns (having owned more than 10), he seems to think the 70s was the golden era of motoring. Current rumours suggest he owns more than 100 caps, prefers Belgium bier to Australian and has been confused with the real Speedy Gonzalez. Well-known at the racetrack for getting maximum performance on a budget and his obsessive attention to detail, he is now taking his passion for all things with an engine to help his customers in his blog. Ask Elvio.