Audi has introduced its third-generation Q7 SUV, a luxury vehicle designed to run on Hydrotreated Vegetable Oil (HVO), a renewable fuel alternative to conventional diesel. This development offers drivers a way to reduce their environmental impact, with HVO capable of lowering net carbon emissions by up to 90% compared to fossil diesel.
HVO is a biofuel produced through a hydrogenation process using renewable bio-feedstocks, typically waste vegetable oils or animal fats. This synthetic fuel is free from sulfur and aromatics and is considered a sustainable option as it does not require farmland for its production. It differs from 'biodiesel,' which is often derived from agricultural crops.
Beyond its reduced carbon footprint, HVO offers several other benefits. It produces fewer harmful particulates than traditional diesel, contributing to better air quality. Rolls-Royce has reported that using HVO can enable reductions in harmful particulate emissions of up to 80% and nitrogen oxide emissions by an average of 8%.
Operationally, HVO is more stable than biodiesel, reducing the risk of filter blockage or water contamination. It can be used as a direct substitute for diesel without requiring modifications to existing engines, typically those up to 10 years old. Audi claims that HVO can also improve engine performance and longevity due to less waste production, potentially leading to lower maintenance costs. The fuel's higher cetane number, which measures ignition quality, is also said to enhance engine performance and reduce consumption.
Carmakers are exploring options like HVO to provide more choices for consumers amid the push towards electric vehicles. Because HVO does not necessitate engine updates and can be mixed with diesel, manufacturers can offer compatibility without significant additional expense. Skoda, for example, states that all its diesel models from the 2022 model year onwards are approved for HVO use. Stellantis, which owns brands like Fiat, Citroën, Peugeot, and Jeep, has also validated all its cars and light-duty commercial vehicles for HVO compatibility. BMW also provides a list of certified HVO-compatible models.
Despite its environmental advantages, HVO is not automatically compliant with all low-emission zone standards, such as London's ULEZ or Birmingham's CAZ. Using HVO does not alter a car's official Euro emissions rating, and enforcement cameras rely on DVLA databases that record the engine's original emissions classification. Therefore, drivers using HVO will not receive official recognition for their eco-friendly choice in these zones.
The availability of HVO remains a significant challenge. While Audi has introduced its HVO-compatible Q7, pumps dispensing this fuel are uncommon at mainstream forecourts, with an estimated 40 to 50 across the UK, primarily catering to commercial fleets. Esso is trialing 25% renewable diesel at around 35 of its sites, mainly in the South East of England. Other providers like AS 24 and Certas offer pure HVO at specific locations, but the future growth of this network is uncertain, mirroring the challenges faced by other alternative fuel infrastructures.
Economically, HVO is typically 10% to 15% more expensive than traditional diesel. The decision to use it is therefore more aligned with prioritizing environmental impact and potential performance benefits over cost savings and convenience.