Barry Ryan was perplexed by the breach, but happy the team had already got through the majority of what it wanted to achieve by the time the pack-up started.
That was even with the regulation changes, although the linear-spring ruling came to light in time for Erebus to get a headstart on 2019 in a post-season Winton test last December.
Known to have often stuck with the simpler linear approach during recent years, Erebus has been tipped by DJRTP boss Ryan Story to benefit most from the rule change, while Craig Lowndes has tipped Reynolds for the title.
More questions than answers
Thursday's timesheets in isolation may point to Mustang domination, but as with testing in most series it never quite paints a full picture.
Track conditions at Phillip Island were better in the morning, for instance, before the temperature rose, and teams worked through their own programs at their own pace.
Not every team or driver had a proper crack at setting a headline time late, and some of the efforts that did come were compromised.