Once a year, the Delsbo Electric contest in Sweden challenges students to create and improve on the world's most energy-efficient vehicles. This year's champ, the Eximus IV, smashed the competition and all previous records with an electric equivalent of 687 MPGe (0.34 l/100km).

Team Eximus, a joint effort between Dalarna University and Chalmers Technical University, has become a bit of a legend in the Delsbo contest, setting new world efficiency records every year from the team's debut in 2016.

The contest takes place on rails, to minimize rolling resistance, and requires contestants to drive some 3.36 km (2.08 mi) carrying six passengers with an average weight of 50 kg (110 lb) per person – a great excuse to get some kids from the crowd involved in the final runs.

Eximus IV's success this year is due to extreme lightweighting and aerodynamics, the team using ultra-light aircraft materials together with a new motor and wheels, and carrying out "extensive wind tunnel testing" despite the fairly slow pace of the "race" you can see in the video below. It wouldn't be difficult to keep up with these things on a bicycle.

But in terms of energy efficiency, they're pretty staggering. Eximus IV's new record is 0.603 watt-hours per person per kilometer. For the entire six-person sled, the efficiency works out around 687 MPGe, or 0.34 l/100km.

Another notable entrant this year was team Levitas, from Chalmers Technical University, which won the HHK Innovation Award with its small, inexpensive take on a maglev system that works on regular train tracks. The team was able to demonstrate a vehicle that can carry a 160-kg (353-lb) weight while keeping a distance of 2 mm (0.08 in) from the tracks.

While team Eximus takes the glory of the main prize this time around, the work the Levitas team has been doing could lead to revolutionary improvements in the affordability of maglev rail systems.

"What these guys have done is a potential game-changer for rail travel," says Paul Bogatir, HHK Cluster Manager and chairman of the Innovation Award jury. "Chalmers has created a cheap, well-functioning magnetic levitating train with an impressive control system. The students even hand-wound some of the magnetic coils to keep costs down. The world should stand up and take notice – this is big."

Check out the competition in the video below.

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