This is the story of one customer’s idea to travel the entire length of the UK on just one tank of fuel!
If you’re thinking this was attempted by some super-efficient 1.2 TDI Audi A2 with an oversized fuel tank, you’d be very wrong…

The customer wanted to see if this was possible in his daily-driven BMW 335d, tuned by ourselves to just shy of 400bhp.



Could a car capable of a sub-12-second quarter mile and a 0–60mph time of just 3.7 seconds really complete this 840-mile trip on a single 57L tank?

Here is the trip in his own words:

One Tank. 840 Miles. Impossible?

The idea was simple, if not a little absurd: drive the length of Britain, from John O’Groats to Land’s End, on a single tank of fuel, almost 840 miles. The car: a 2017 BMW F30 335d xDrive. A twin-turbo straight-six diesel pushing 394bhp and a monstrous 915nm of torque. Built for autobahns, not sipping fuel like a monk. German engineering stubbornness. Not your typical hypermiler. On paper, impossible. Required average: 66.9 mpg. Numbers that people would laugh at in a BMW twin-turbo. One man, one machine, one tank, and a thousand miles of doubt.

Preparation

Just shy of 839 miles, according to the BMW app. Possible? Probably not. Attempted? Almost certainly not, until I decided to try. The tank was brimmed the night before at the John O’Groats filling station. I parked at the campsite next door, knowing I’d need every ounce of rest before the challenge. At 3:14 a.m., I set off from the famous John O’Groats sign. The car’s trip computer showed a range of just 466 miles, barely half the distance I needed to cover. The best figure I’d ever seen before this was around 720 miles for a single tank. With 840 miles between me and Land’s End, optimism was in short supply.

The Early Hours

By 7:02 a.m., I’d covered 140 miles and stopped for breakfast. The trip showed 64.3 mpg, 584 miles of range, and 704 miles still to go. Impossible numbers, but better than expected. At 9:32 a.m., things looked even more surreal: 235 miles in, averaging 67.1 mpg, with 600 miles of range showing and 603 left to Land’s End.

Midday Momentum

By early afternoon, I’d crossed 405 miles. The figures were astonishing 71.1 mpg and 488 miles of range left, with just 433 to go. Over lunch, I allowed myself to believe I was really going to make it. But the road ahead was long, and anything could still happen.

When It All Went Wrong

Between Liverpool and Manchester, everything unravelled. Standstill traffic. The mpg figure plummeted, and the extra range I’d worked so hard to achieve began to evaporate. At 488 miles, crawling back into motion, the numbers had dropped to 65.1 mpg 328 miles of range left, 350 still to cover. The odds had flipped. Southbound through Birmingham, the M5 proved no kinder. Gridlock again. But oddly enough, this time 40 and 50mph restrictions helped rather than hindered.

Clawing Back Hope

By 597 miles, the average had surged to 76.1 mpg, with 292 miles of range and only 244 left to Land’s End. Against all logic, the car was clawing back hope. By 8:13 p.m., after 682 miles and another much-needed break, the BMW was showing 77.1 mpg, just 159 miles to go.

The Final Stretch

At 796 miles, disaster nearly struck. Roadworks on the A30 forced a diversion. Two choices: follow the app or trust the road signs. With no idea how far the detour might stretch, I gambled on the BMW app. Fortune, for once, was on my side. The trip read 76.8 mpg, 94 miles of range, and just 31 miles left to Land’s End. At 11:14 p.m., after 845 miles of tension, traffic, diversions, and disbelief, the Land’s End stones rolled into view as I pulled up alongside the front of Land’s End. The trip computer showed 76.5 mpg, with 56 miles of range remaining.

Proven. Not Possible, But Done.

One tank. John O’Groats to Land’s End. Of course, there was still the matter of fuel. The light came on as I headed toward Penzance, where I finally filled up.

Final Results

• Total distance covered: 857 miles
• Fuel used: 53.99 litres (11.87 gallons)
• Real-world economy: 72.16 mpg

Not just possible. Proven. Exhausting, exhilarating, improbable, and utterly unforgettable.