In an effort to curb tailpipe emissions of standard petrol and diesel vehicles, governments have introduced increasingly stringent regulations of noxious emissions for vehicle manufacturers to meet. The tests involve running the engine in a laboratory setting under defined conditions, including speed, load and temperature. All new cars sold must comply with the emission requirements.

The vehicle manufacturers have generally resisted tighter standards, on grounds of technical feasibility and production cost. Nevertheless, they have developed new technologies, most importantly the catalytic converter for petrol (gasoline) engines, now standard, which converts noxious exhaust gases into less harmful species, in particular converting toxic NOx to inert nitrogen. Because the catalyst is poisoned by the lead additive that used to be included in petrol to improve combustion, lead was eliminated from petrol. This was doubly desirable because lead is a toxic substance.

The context for electric vehicle development

Following regulation to tackle health impacts, the need to reduce transport carbon emissions, to counter the risk of global warming, has led to regulatory action to improve fuel economy. Transport is responsible for a quarter of Britain’s greenhouse gas emissions, and road transport accounts for 90 per cent of this. Voluntary CO2 emission standards were introduced in the European Union in 1998 and became mandatory in 2009. The 2015 target of 130g CO2 per km for new passenger cars was met in advance in the UK. By 2021, the requirement will be 95g, averaged across manufacturers’ new fleets of vehicles. This in effect requires manufacturers to market zero, or ultra-low, emission vehicles to offset the carbon of conventional vehicles.

Concerns about both urban air quality and carbon emissions prompted the British government to commit to a “mission” for all new cars and vans to be effectively zero emissions by 2040, which involves ending the sale of new petrol and diesel cars and vans by that date and ensuring that at least 50 per cent of new car sales are ultra-low emission by 2030. Other European governments have also adopted target dates to phase out oil fuels for road transport: for instance, France by 2040, the Netherlands, Austria and Ireland by 2030 and Norway by 2025.