As the final two days of preseason testing approach, stark choices must be made. For the three Formula E constructors facing troublesome technology, time is fast running out. On Tuesday, they must gamble: do they stick with their new powertrains and risk humiliation in Beijing if they don’t work, or revert to the season one package and risk running at the back of the pack for the entire season?

Difficulties with new technology are not unexpected. If anything, it’s been rather more impressive to see just how reliable several of the new powertrains appear to be.

While the units in the backs of the Mahindra, Venturi and Dragon cars are upgraded versions of last year’s packages and come with the might of McLaren and Hewland support, the teams have still had to get their software programming and chassis adjustments right. They appear to have done just that.

DS Virgin, Renault and ABT have gone for very different solutions, with one, two and three gear versions and motor manufacturers other than McLaren. These appear to be the three front runners. The ABT offering, in particular, has been described as “bullet proof” and is incredibly fast too.

The three teams who’ve had a tough time of it at Donington Park are Trulli, Amlin Andretti and NextEV TCR but their situations are quite different.

The NextEV squad took full advantage of the 15 days of private track testing that were on offer to constructors, without problems to report, so it’s unlikely that there’s anything fundamentally wrong in that camp. Proof of that can be seen in Nelson Piquet’s decision to stay with the team, despite being connected to the Virgin team and its new OEM partner.

The Andretti people insist that their powertrain issues come down to software issues and that they’ve nearly cracked it. Even so, they’ve done hardly any running and look to be on shaky ground.

Trulli hasn’t even emerged from the garage yet and there’s no word as to what the situation is.

Here are the decisions that those constructors must make by Tuesday:

1. Revert to the S1 package. While this could be seen as the safest option, it’s already very clear that the front running teams have found considerable track time in their new powertrains, so sticking with season one tech is very likely to rule out any chance of podiums and almost certainly discount any chance of bagging driver or team titles. That’s unlikely to play well with sponsors and drivers. Trulli struggled in particular with their S1 powertrain and won’t fancy a re-run of the first season. Andretti were pretty strong with their S1 set up but it would be a backwards step. The same goes for NextEV.

2. Purchase another powertrain solution. The deadline to purchase a powertrain from another constructor has already passed but, because the good of the entire sport is at stake, there’s still a remote possibility that this could be permitted. The chance to sell equipment to another team would be of interest to the constructors to help balance the development budget, of course. However, the FIA, FEH and every team would likely have to all agree this rule change, which seems unlikely: the three front running teams won’t want to cede any competitive advantage. The elephant in the room is Team Aguri, which is the only team on the grid to have elected to stick with the S1 package. It’s hard to see them agreeing to allow a competitor to possibly leap frog them by switching to another powertrain at this late stage.

3. Stick with the new solution. Article 3.4 of the 2015 technical regulations (2015 Formula E regulations (July 2015) ) allows FIA-approved changes to hardware already homologated: “Exceptional changes for the purpose of improving reliability or safety may be approved by the FIA and/or after full consultation with all other manufacturers…A minimum of 30 days is required between a Technical Note request regarding modifications of safety, reliability or driver comfort made to a car and its presentation at scrutineering before an event.” So NextEV could, for example, swap its twin-motor configuration for a single motor solution, continue with dyno testing (the test chassis is not allowed to be used) and ship the modified powertrains to Beijing separately from the main tranche of cars. The teams are also allowed to continue working on software, so Andretti could carry on tinkering on their computers until Beijing to iron out those glitches.

What all stakeholders will keep in mind is that motorsport is primarily about entertainment, and having three teams completely out of contention does not make for good viewing.

Our view? Andretti and NextEV will probably stick with their own solutions. Trulli’s issues might best be solved by allowing the Italian team to purchase one of the new powertrains, one that has been thoroughly track tested (which theirs hasn’t). A Mahindra or Venturi power unit would the obvious choice (closest to S1 parts, so less for the Trulli team to try and learn overnight).

With pressure mounting and just a few days left until the deadline, Monday and Tuesday are going to be fascinating. We’ll be trackside as usual. Don’t miss our coverage.