Honda has claimed a new Guinness World Record, for the "Lowest fuel consumption – all 24 contiguous EU countries (all cars)." Although that's a bit of a mouthful, it simply means that the carmaker achieved the highest fuel efficiency ever recorded while traversing all 24 adjoining EU countries.
A Honda Civic Tourer 1.6 i-DTEC driven by two members of Honda’s European research and development team, Fergal McGrath and Julian Warren, recorded an average 100.31 mpg (2.82 l/100 km) over the 8,387-mi (13,498-km) journey. The journey began on June 1 and lasted for 25 days, taking a clockwise route through the continent before bringing the drivers back to their starting point.
McGrath and Warren's feat is reminiscent of Audi and the RAC's recent record-breaking journey through 14 countries in Europe on a single tank of fuel. Unlike that achievement, however, the drivers refueled nine times, averaging 932 mi (1,500 km) between each fresh tank.
Honda explains that the challenge was aimed at demonstrating the real-world fuel economy of the Tourer. Under the rules of the record attempt, the car had to be a standard model in every respect and fueling was carried out at regular filling stations.
The car's tire pressures and wheel alignment were optimized, however, and McGrath and Warren took steps to ensure their driving was efficient, including accelerating and braking smoothly, anticipating road conditions ahead, carrying no unnecessary weight and ensuring the vehicle was well maintained.
Source: Honda
IOW, regular car drivers have no way to hit that 3l/100km mark.
Which means that the only way to get to 1l/100km is to build much lighter cars with much less powerful engines.
Motorcycles are extremely unsafe to commute on in traffic and not many people opt for cars even as small as the Smart ForTwo and while some people might be drawn to their efficiency most women find them ugly.
So if you have kids they are probably too small and if you are single they are too nerdy and no matter your circumstance they probably aren't as safe as SUV's. Owning one likely means you already own other vehicles and are picking up a 2nd or 3rd. I think if there was huge demand for such vehicles we would see more small cars on the road.
They seem to have more appeal in car rental services like Zipcar.
I'm assuming that it was considerably lower than a normally tolerant person would deem reasonable in our time-constrained world.
Such a test will only mean anything, if the travel was performed at (approaching) normal highway speeds (ie. 100km/hr as a minimum standard).