A BMW 116d EfficientDynamics five-door hatch broke the 100 mpg barrier when it achieved 2.7 litres per 100 km over the 102 km Brighton to London route at the recently concluded 2012 RAC Future Car Challenge, winning it the Best Internal Combustion Engine accolade.

Despite the route’s fair share of hilly sections and busy city traffic, Green-Car-Guide.com’s Paul Clarke and Paul Andrews managed a 39% improvement over the official 3.8 litres per 100 km combined economy figure.

“Hybrids and electric cars certainly have an important future, but it shows that people shouldn’t write off the internal combustion engine yet, as its efficiency is improving all the time,” said Paul Clarke, founder and editor of the green car news website.

With a starting price of £20,355 (RM100k) for the three-door and £20,885 (RM102k) for the five-door, the eco-friendly 1 Series hatchback emits a low 99 grams of CO2 per km and therefore qualifies for zero Vehicle Excise Duty in the UK and is London Congestion Charge-exempt. The century sprint is executed in 10.5 seconds and top speed is over 190 km/h.

First held in 2010, the Brighton to London RAC Future Car Challenge is an annual showcase of both current and future low energy use vehicles, including electric, hybrid, hydrogen and low-emission conventional petrol and diesel cars.