Glossary of key terms

Do you know your BiK from your VED? And your WLTP from NEDC?

Vehicles. They all come in different shapes and sizes, with different engines, options and fuel types. Then there’s company car tax, Clean Air Zones and the all-new Ultra Low Emission Zone to consider. But, don’t worry!

Our glossary is an easy reference for some of the key terms you may have heard…


AFVs are vehicles that are powered by something other than just traditional petroleum fuels (petrol or diesel). This includes electric cars, hybrid electric vehicles, solar powered, propane and biodiesel.

A ULEV is a vehicle that emits extremely low levels of emissions when compared to other vehicles – 75g/km CO2 or less.

The Office for Low Emission Vehicles (OLEV) is providing over £900 million to position the UK at the global forefront of ULEV development, manufacture and use.

Hybrid vehicles are powered by combining a petrol or diesel engine with an electric motor.

WLTP is the new test procedure to measure the emissions and fuel consumption of a vehicle. It has been introduced to achieve an internationally standardised measure across passenger vehicles and light commercial vehicles that seeks to be more realistic for consumers.

From April 2020 company car tax and vehicle excise duty will be based on the Worldwide Harmonised Light Vehicle Test Procedure (WLTP) reported CO2 emissions figures.

Find out more.

The old test procedure, now replaced by the new WLTP measure.

The RDE test measures the pollutants emitted by cars while driven on the road to verify that legislative caps for pollutants such as NOx are not exceeded.

– RDE step 1 (NOx conformity factor of 2.1) has applied since 1 September 2017 for new car types and all types from September 2019
– RDE step 2 (NOx conformity factor of 1.0 plus an error margin of 0.5) will apply in January 2020 for new types and from January 2021 for all types

Vehicles with a petrol or diesel engine produce carbon dioxide gas (CO2). The level of emissions indicates how much CO2 is being emitted. CO2 emissions affect the amount of BiK and VED payable.

Search for fuel consumption, CO2 emissions, and tax bands for new and used cars –

The MOT test checks that your vehicle meets road safety and environmental standards.

An MOT is required by either:
– the third anniversary of its registration (generally)
– the anniversary of its last MOT, if it’s over 3 years old

Some vehicles require an MOT after 1 year. Find out more –

P11d is the list price of a car including factory options, VAT and delivery, but not including the first registration fee or VED.

Tax & Legislation

VED or ‘car tax’ applies to every vehicle using public roads in the UK and is collected by the Driver and Vehicle Licensing Agency (DVLA). Rates are based on either engine size (registered before 1 March 2001) or fuel type and CO2 emissions (registered 1 March 2001).

Diesel cars that meet the RDE2 standard pay a lower rate VED than those that do not.

View the VED rate tables –

BiK is a tax on employees who receive benefits that are not included in their salary. If you’re driving a company car for private use or if you order a salary sacrifice vehicle, you’ll pay BiK. Private use includes journeys between home and work.

The amount of BiK payable is defined by HMRC and is based on CO2 emissions, P11d value and your personal tax band.

For diesel cars there’s a 4% supplementary charge based on the P11d value of the car. This does not apply to RDE2-certified diesel vehicles.

A licence check shows what information DVLA holds about your driving licence. This includes your driving record, penalty points or disqualifications. Licence checks are required for yourself and anyone else (e.g. nominated drivers) who may drive a vehicle provided by Zenith.

A motor insurance ‘green card’ is an internationally-recognised document that acts as proof that a driver is insured to drive abroad. This can be requested from the insurer, usually about a month before you intend to travel.

Find out more. 

When driving abroad, you might need to display a GB sticker, or GB sign on your number plate. GB is the distinguishing sign to display on UK-registered vehicles when driving outside of the UK.

Find out more.

Clean Air

A CAZ defines an area where targeted action is taken to improve air quality in a way that delivers improved health benefits and supports economic growth. This can include a city, area or road in which vehicles can be charged or fined for entering.

There are four classes of CAZ:
Class A – Buses, coaches, taxis and private hire vehicles
Class B – Buses, coaches, taxis, PHVs and heavy goods vehicles (HGVs)
Class C – Buses, coaches, taxis, PHVs, HGVs and light goods vehicles (LGVs)
Class D – Buses, coaches, taxis, PHVs, HGVs, LGVs and cars

Cars, vans and taxis that meet Euro 6 (diesel) or Euro 4 (petrol) emissions standards are exempt from any charges or restrictions.

Five cities have been mandated by the Government to introduce a Clean Air Zone; Birmingham, Leeds, Nottingham, Derby and Southampton. The government has also named 23 local authorities that must carry out a feasibility study to determine whether a CAZ is required.

CAZs must have signs in place along major access routes to clearly delineate the zone.

The ULEZ replaced the T-Charge in London on 8 April 2019.

Drivers entering the capital in vehicles that don’t comply with new emissions standards will have to pay a fee 24 hours a day, 7 days a week every day of the year. This is in addition to the £11.50 congestion charge, which is currently payable between 7am and 6pm, Monday to Friday.

Find out more.