Behind the acronyms – ULEVs explained

ULEV in nottingham

So you want to buy a greener car but you don’t know where to start? We’re here to explain the acronyms and help you get to grips with the various types of Ultra Low Emission Vehicle available.

Let’s start with the basics…

What is an ULEV?

An Ultra Low Emission Vehicle (or ULEV), is any vehicle that produces less than 75g of CO2 per km driven and is able to drive for 10 miles without emitting any CO2. At Nottingham City Council we are helping support citizens to make the switch to ULEVs through our Go Ultra Low programme.

Fully Electric Vehicles (EVs)

The most straight forward to understand are fully electric vehicles, which are are powered by stored electrical energy. This energy store is contained within a battery pack which transfers the electricity to a motor, and in turn provides the propulsion through the wheels.

Examples include the Nissan LEAF, Kia Soul EV and any Tesla.

Range Extended Electric Vehicle (REx or REEV)

A range extended vehicle runs on electricity but includes an auxiliary power unit known as a ‘range extender’ – usually a small petrol engine – which charges the battery and allows these vehicles to travel greater distances between charges.

Although range extended vehicles contain a petrol engine, they are not classed as hybrids as the petrol engine is used to charge the battery not drive the car.

These vehicles will emit some CO2 when the range extender is in use but typically this is well below the emission standards, so these vehicles can still be classed as Ultra Low.

Examples include the BMW i3 Rex and Vauxhall Ampera E-REV.

What about hybrids?

There are two types of hybrid. Those you plug in and those you don’t.

Although both types can work on electric-only mode, almost all conventional hybrids aren’t ULEVs. The battery is much smaller in a conventional hybrid and is charged via regenerative braking and coasting, therefore having a very short electric range – usually around 1 mile. This is why the second part of the ULEV definition – the ability to drive 10 miles without emitting CO2 is so important. This criteria draws a clear line between regular hybrids and plug in hybrids and ensures the term ULEV is reserved for the cleanest cars.

Plug in hybrids (PHEVs) on the other hand are ULEVs and can either be charged in the same method as conventional hybrids and/or be plugged in to a charge point. This allows them to have bigger batteries which provide more power to drive the vehicle to around 40 miles depending on the model.

PHEV models offer more flexibility – featuring the benefits of a battery electric vehicle’s motor, making it great for inner city driving, while being combined with the range of a petrol or diesel engine when required.

Examples include the Mitsubishi Outlander PHEV, BMW i8 PHEV.

Fuel Cell Electric Vehicles

Hydrogen Fuel Cell Electric Vehicles (FCEVs) combine hydrogen and oxygen to produce electricity, which in turn powers the vehicle. This results in zero tailpipe CO2 emissions since heat and water are the only by-products of the reaction.

The on board hydrogen tank can give the vehicle a range of 300 miles or more (similar to a conventional petrol car), with only a few minutes required to refill the tank.

The benefits of FCEVs is that they have zero tailpipe emissions but also have the range and refuelling convenience of conventional cars. There is a downside however, as refuelling stations are not widely available in the UK.

Examples include Huyndai Nexo, Honda Clarity Fuel Cell, Toyota Mirai etc.