Maastricht, the Netherlands - Long-distance fuel-efficiency runs demand more than feather-footed driving skills; you need immense concentration for long periods as well.
So here's a 'hats off' to British motoring journalist Andrew Frankel and racing driver Rebecca Jackson, who've just earned themselves - and Audi's A6 2.0 TDI S-tronic ultra - a place in the Guinness book of records for the most number of countries visited on a single tank of fuel.
They left Maastricht at 9.48am on Tuesday 9 June and finally rolled to a stop just inside the Hungarian border at 12.44pm the next day, after 28 hours of almost non-stop driving that took them through Belgium, Luxembourg, France, Switzerland, Lichtenstein, Austria, Germany, Italy, Slovenia, Croatia, Bosnia and Serbia along the way - 14 countries in all.
That's 1854.24km on 73 litres of diesel, for an average fuel-consumption of 3.94 litres per 100km - the kind of numbers you'd expect from a moped, rather than a luxury sedan, and even better than Audi’s ‘combined-cycle’ quote of 4.22 litres per 100km.
And that was after they'd been faced with a number of real-world challenges on the drive, including diversions for heavy traffic and a closed tunnel, which resulted in a unplanned, heavy-on-fuel mountain detour.
CLIFF-HANGER FINISH
Co-ordinator Simon Williams admitted the last stretch was a cliff-hanger, with the Audi's trip computer reading “Range: 0km” for the final 26 kilometres to the Hungarian border.
Frankel admitted afterwards: "The challenge turned out to be much harder than Rebecca or I imagined it would be.
"Despite sharing the driving we were on the road almost continuously for 28 hours, focused on maintaining an average speed of around 80km/h. To do that you have to be fully aware of what's going on around you and anticipate what could happen with the traffic ahead.
"It was normal driving in one sense, but it was also a very different and demanding type of driving."
Jackson added: "I'm usually known for driving pretty fast, but this challenge was more about maintaining a constant, fuel-efficient speed and not being caught out by vehicles that made us slow down and then have to accelerate to the optimum speed again.
"It was a very different long-distance driving challenge to what I'll be doing next year when I compete in the 24 Hours of Le Mans 2016."
The 'ultra' badge is reserved for the most fuel-efficient versions of Audi's diesel-powered cars; so far only the A3, A4, A5, A6, A7 Sportback and TT coupé have qualified to wear it.