How you can follow the King’s lead and reduce your car’s fuel usage
Leading by example is a life lesson we’re all taught. But for our monarch, King Charles III, it’s the opening sentence in the job description, particularly when it comes to sustainability.
With news that the Crown Estate’s profits soared last year to £1.1bn, thanks to the granting of six licences for new offshore wind farms, the Royal family is now in line to receive a £45m boost to the Sovereign Grant. While a significant part of that will pay for renovating Buckingham Palace, the King is set on ensuring some of that money furthers his sustainability aims, particularly when it comes to their fleet of cars.
For most families in the UK, emissions and everyday fuel bills continue to rise, and the Royal family is not exempt. Petrol prices peaked at an average of £1.50 a litre in April 2024, according to the AA motoring group, raising the cost of everyday life for regular motorists and royals alike. While rising fuel prices might not be a massive issue for the Royal household, the King’s brace of state Bentley State Limousines (first presented to the late Queen Elizabeth II in 2002 for her Golden Jubilee) will be converted to run on E85 biofuel within the next year, as part of a wider sustainability push.
Regular unleaded petrol is branded E10, denoting a 10 per cent bioethanol, so the move to a fuel containing 85 per cent of low environmental impact is significant.
Already ahead of the game when it comes to car conversions, the Bentleys follow in the tyre tracks of King Charles’s beloved Seychelles Blue DB6 Mk2 Vantage Volante, which underwent conversion to biofuel back in 2008.
“I’ve got electric cars now, but it’s been so difficult,” King Charles told the BBC in an interview. “My old Aston Martin, which I’ve had for 51 years, runs on – can you believe this – surplus English white wine, and whey from the cheese process.”
Until now, both Bentleys were powered by potent twin-turbocharged, 6.75-litre V8 engines, modified from the company’s Arnage R. With the Crewe-based marque looking after the conversion process, it’s hoped the switch will lessen the cars’ carbon output as well as their running costs. Equipped with a “panoramic glasshouse” to offer greater visibility from the outside, each car measures more than 80cm longer than the Bentley Arnage on which it is based. It was widened and had the roof raised high enough for the late Elizabeth II to walk in and out without stooping, not to mention the Kevlar-reinforced tyres and flashing blue lights to cut through the traffic if needed. With a blast-resistant cabin that can be sealed airtight in the event of a gas attack, Bentley left no stone unturned when it created the limousine at the turn of the century but now the carmaker is tasked with making the maroon-coloured car a little greener.
Bentley confirms the cars will be E85 compatible when the conversion is complete, meaning both will be powered by petrol that’s made up of 15 per cent regular unleaded and up to 85 per cent ethanol, a type of alcohol obtained from plants rich in cellulose.
Despite the unfamiliar mixture and name, E85 fuel is nothing new. With roots dating as far back as the early 1900s and the birth of the motor car, Henry Ford’s Model T, built from 1908 to 1927, featured carburettor jets that could be adjusted to let the engine run on petrol, ethanol, or a mix of the two – something we now know as a fuel-flex car. Back in 2006, Morrisons supermarket opened the UK’s first E85 retail filling pump in Norwich, in line with the first deliveries of the Saab 9-5 BioPower flex-fuel, hoping to capitalise on a move to biofuel.
But it never caught on. “Despite being introduced around a decade ago, E85 is no longer commercially available in the UK although it remains widely available on forecourts across Europe, often called bioethanol E85,” says the RAC. Falling out of favour due to the space required to grow the crops for the fuel being needed for food production in the UK, E85 fuel is almost impossible to come by commercially in the UK today, as are the conversion kits required to run it.
One can only assume that Bentley and the Royal Family have ways around this supply issue.
While access to E85 fuel might not be an issue for a monarch who doesn’t cover many miles, given his mother’s 2012 Bentley Mulsanne was sold in 2016 with less than 6,000 miles on the clock, there are other options for regular motorists looking to convert to something more sustainable and cost-effective.
Liquid Petroleum Gas (LPG) conversions have been around for some time, gaining traction as a popular alternative to petrol and diesel in the 2000s due to a government incentive, which covered some of the conversion costs. But the scheme ended in 2005 and the number of LPG conversions dropped ever since.
While converting a car to run on LPG costs between £1,200 and £2,000, “your fuel costs could ultimately be cut in half,” says insurance company Howden, with LPG costing around half the price of petrol. It’s also more environmentally friendly, emitting less CO2 and, more significantly, hardly any black carbon – the sooty material that comes from other engines that burn fossil fuels. Despite the benefits, LPG conversions have continued to decline, largely due to LPG pumps increasingly being swapped for electric car (EV) chargers.
In line with the move to electric, the Royals have stated their longer-term ambition is to switch to a fleet of official electric cars after the conversion of the two Bentleys. With more companies pivoting to electric conversions in recent years, the monarch might be able to stick with his beloved Bentleys for a little longer.
Last year, Oxford-based firm Electrogenic converted actor Jason Momoa’s 1929 Rolls-Royce Phantom II to electric, replacing the original 7.7-litre straight-six engine to a “whisper-quiet” electric powertrain.
“I needed a team that would appreciate the storied history of this car while updating its technology,” said the star to the BBC at the time. While the project was a one-off, it showcases the company’s commitment to converting classic cars to more sustainable means of propulsion.
For other owners looking to convert their pride and joy, the firm will take on most pre-90s cars for conversion. For anything younger, it’s usually not worth the cost, says the firm, considering that cars became increasingly complex after this time. However, models that kept their simplicity all the way to the end of their runs, like the classic Land Rover Defender (2015) and the original Mini, are still possible candidates for electric conversion.
When it comes to cost, Electrogenic’s classic Mini kit starts at £15,000 (+VAT) for something you’d install yourself, but for more bespoke and high-powered projects, the cost can quickly top £100,000.
While recouping the cost of electric conversion can take time, particularly for a high-performance car, the fuel savings can be significant. For a Rolls-Royce Silver Shadow produced between 1965 and 1980, Electrogenic estimates the fuel cost to be £0.04p per mile on electric compared with £0.52p per mile with a traditional petrol powerplant.
While the Royal family cracked on with biofuel conversions under King Charles’ watch, there will come a time – very soon, perhaps – when the King’s fleet will be forced to make the switch to something even more sustainable.
For now, the Royal family might struggle to make the switch to electric given their current access to infrastructure; a familiar issue to the many every day EV drivers. A recent survey by Carmoola showed that Buckingham Palace has only seven fast-charging points within a mile, with three out of service at the time of writing. At Windsor Castle, there are only two fast chargers within a two-mile radius. At Balmoral, it’s an even bleaker picture – the nearest fast charger is more than 24 miles away.
With charging infrastructure being cited as the greatest obstacle to greater EV take-up, it seems the King’s decision to eke out the combustion engine might have been the right one.