In the next wave of the competition, however, it appears there's no more holding back.

SpaceX has released the rules for its 2018 Hyperloop Pod Competition, revealing there's just one thing the teams will now be judged on: 'maximum speed.'

'The competition will be judged solely on one criteria: maximum speed with successful deceleration (i.e. without crashing,' the first revision of the 2018 rules and requirements states.

Aside from this, there's just one other rule, which says that all of the pods must be self-propelled.

This means SpaceX will not be providing any pushers for the tests. 

For the 2018 wave of the Hyperloop competition, only student teams are eligible to enter, including returning teams who have built a new pod, or modified their previous device.

The selected pods will eventually compete at the test track.