Glossary of Automotive Terms – Z

Letter Z – Dictionary of Automotive Terms

  1. A letter rating for tires to indicate that they are theoretically rated for speeds over 300 kph (186 mph), as in P245/50ZR16. There is no higher rating, but the one lower rating is Y
  2. The symbol for Impedance
Zahnradfabrik Friedrichshafen


A rear axle introduced with the BMW Z1 in 1988, consisting of a trailing arm, one upper lateral link, one lower diagonal link, and a coil spring at each side; also included is an anti-roll bar
A striped hardwood used for interior trim as a cheaper alternative to burr walnut
A striped hardwood used for interior trim as a cheaper alternative to burr walnut
When a frame is cut, usually in front of the rear wheels, and a section is welded in to raise the axle so large tires can be used at stock body heights, racers say their car has been z’ed [pronounced ZEED, not ZED], referring to the new appearance of the frame.
Zener diode
A semiconductor used on British Motorcycles for many years as a Voltage regulator. When the Voltage across the Zener Diode reached a certain point, the element would begin to conduct current, routing it to ground, thus preventing the Battery from overcharging.
Pearl Izumi’s highly wind resistant, water repellent, lightweight fabric that keeps the cold wind out and maintains breathability.
Zerk fitting
A small valve that allows grease to be added to a Ball joint with a Grease gun and prevents the grease from leaking out when pressure is placed on the area. Incorrectly pronounced zert. Also called Grease fitting
An amount or reading (often set arbitrarily) where there is an absence of value or which is the beginning of something.

Zero absolute pressure
A total vacuum. Zero on the absolute pressure scale
Zero-emission vehicle

  1. A vehicle which itself produces no emissions, such as electric powered vehicles. The concept does not take into account the fact that electric cars use the electric power of batteries that are normally charged by power supplied by electric power plants (which generally do produce certain emissions); Californian laws require that from 1998, 2% of new cars must be ZEVs.
  2. A vehicle meeting either EPA’s CFV ZEV standards or CARB’s California Low-Emission Vehicle Program ZEV standards. ZEV standards, usually met with electric vehicles, require zero vehicle (not power plant source) emissions. ZEVs earn more Clean-Fuel Fleet Vehicle Program credits than ULEVs. ZEVs may also meet ILEV standards.
  3. A vehicle that is certified to meet the most stringent emission standards established by the California Air Resources Board (CARB). These standards require zero regulated emissions of nonmethane organic gases (NMOGs), carbon monoxide (CO) and nitrogen oxides (NOx). A ZEV is most likely powered by electricity, fuel cells, or hydrogen.
Zero governor
A regulating device that is normally adjusted to deliver gas at atmospheric pressure within its flow rating.
Zero ice
Trade name for dry ice.
Zero line

Zero offset
Zero-offset steering
A Steering system whose geometry has a Scrub radius of zero. This configuration minimizes the steering effects produced during acceleration (with front drive) or braking on varying Traction surfaces.
Zero point
When considering a three-dimensional object (such as the body of a car), the zero point is the middle of its length, width, and height.
Zero-velocity spreader
A spreader that uses air flow to dispense chemicals (liquid and/or dry deicers) in a continuous controlled pattern with material blown onto the road in one direction at approximately the same speed the truck moves in the other direction. The deicing materials strike the pavement at zero velocity and stay where they fall.
Abbreviation for Zero-emission vehicle


An abbreviation for Zahnradfabrik Friedrichshafen, which is a German company that manufactures transmissions and Transaxles used in many exotic, high performance, and racing cars.

Zigzag spring
zigzag springZigzag spring

A serpentine type of spring used in seat construction

A metallic element used in galvanizing metals, die casting, as a constituent in various alloys, as a battery electrode, etc.

Zinc alloy
An alloy whose main component is zinc
Zinc bath
Zinc electroplating
Zinc immersion treatment
A pretreatment before electroplating a thin zinc deposit forms by immersion of aluminum in a zinc solution which prevents further oxidation of the aluminum and provides a key for the galvanic coating
Zinc-iron alloy layer
An alloy layer formed on iron and steel during hot-dip galvanizing as a result of the diffusion of atoms from the molten zinc into the work and vice versa
Zinc phosphate coating
A zinc-rich conversion coating produced by phosphating
Zinc plating
The application of a zinc coating by galvanizing or electrogalvanizing
Zinc-rich paint
Paint containing an extremely high proportion of metallic zinc dust in the dry film (about 95% by weight), applied to iron and steel as an anti-corrosive primer; the application of zinc-based primer may be regarded as a less durable form of cold galvanizing
Zinc-rich primer
Paint containing an extremely high proportion of metallic zinc dust in the dry film (about 95% by weight), applied to iron and steel as an anti-corrosive primer; the application of zinc-based primer may be regarded as a less durable form of cold galvanizing
The trademark of a special type of coil-coated steel sheet with plastic and zinc dust coating, which is proving increasingly useful in automobile manufacture
Zinc spraying
A process for applying zinc coatings to iron and steel. Particles of molten zinc are sprayed on the surface to be coated; the coating metal, usually in the form of wire, is fed into a spray gun, in which it is melted by the combustion of a fuel gas, e.g., a mixture of oxygen and acetylene. The molten metal is atomized by compressed air and precipitated on the surface to be coated at high velocity
Zinc technology
Zinc vapor deposition
(ZYD) A process in which zinc vapor is deposited in a vacuum on the pieces being worked on
Zipper merge
A merging procedure which is necessitated when a multi-lane highway is about to be reduced to a single lane because of construction or accident. All traffic is allowed to use both lanes until reaching the merge point. Then the vehicles in the left and right lanes take turns alternatively as they move into the single lane. The procedure duplicates the action of a zipper as it is secured. Zipper merge prevents road rage since everyone is reduced to equal opportunity to merge.
A plastic strap that, when threaded through its end and pulled, tightens and stays tight to affix cables or number plates to bicycles, or to securing wiring on vehicles.
Zirconium oxide, used in enamels and ceramic coatings
A metallic element. Symbol Zr; atomic number 40
A euphoric state of mind experienced when riding a bike and everything is going right.

Zone controls
Controls used to maintain each specific area or zone within a building at a desired condition. This is a type of distribution control often used in hydronic heating system.
Zone Switch
Trucker slang for Highway patrol headquarters as in ‘Better be careful the zoo is empty tonight.’


Abbreviation for Zinc vapor deposition