Average monthly fuel prices in Northern Ireland 2017-2022, by fuel type

Diesel was the most expensive conventional motor fuel in Northern Ireland in September 2022, at 178.6 pence per liter. The prices of unleaded 95 octane, diesel, and super unleaded fuel in Northern Ireland have fluctuated greatly. As the Russia-Ukraine war brought about greater oil and gas supply constraints, fuel prices reached a peak in June 2022, with diesel prices at 194.1 pence per liter.

UK diesel car sales in decline

When looking at the fuel types of new cars registered in the UK, diesel has notably fallen out of favor. In 2018, nearly a third of all newly-registered passenger cars were powered by a diesel engine. By 2021, this figure had decreased to less than 10 percent. Diesel's decline has largely come about due to greater popularity of alternative fuels, a shift in consumer preference that has also impacting petrol car sales. The combined share of battery electric and hybrid-electric vehicle sales stood at nearly 20 percent in 2021.

The energy crisis of 2021/22

Motor fuel prices have risen to new highs in the wake of the Russia-Ukraine ware, which brought crude oil prices to highs not seen since 2008. Refined petroleum products such as gasoline and diesel are largely informed by the price of crude oil. Refining and marketing costs as well as taxes have a lesser influence on retail prices. Motor fuel prices are not the only energy prices that have increased significantly since late 2021. Rising natural gas wholesale prices have also led to an upped price cap on annual energy bills, with the default energy tariff price cap set at 3,549 British pounds as of October 2022.