The huge plumes of smoke being emitted by the Ferrari-powered cars was one of the more unusual elements of 2018 pre-season Formula 1 testing at Barcelona.
Rather than being a one-off occurrence, the sight of a cloud of smoke engulfing the Ferrari part of the pitlane just prior to its car emerging become commonplace - and was seen with customer teams Haas and Sauber too.
It left some in the paddock speculating that Ferrari might be deploying some form of engine trick.
But it appears the smoke was in fact a consequence of new F1 regulations brought in this year to clamp down on 'oil burn', something that Ferrari was believed to be particularly active in last year.
As well as new requirements to help the FIA monitor the amount of oil that teams are burning, other tweaks to the rules have been introduced regarding the piping of oil vapour from catch tanks.
Previously it had been possible - through the use of active control valves - to feed this vapour back into the car's airbox, where it could then be sent into the engine and burned for a power boost.
Two new 2018 rules now prohibit such behaviour and force teams to feed out any excess oil vapour from the back of the car.
Article 5.1.12 of F1's technical regulations states: "All power unit breather fluids may only vent to atmosphere and must pass through an orifice which is positioned rearward of the rear axle centre line and less than 400mm above the reference plane and less than 100mm from the car centre plane. No breather fluids may re-enter the power unit."
Article 7.8 adds: "The use of active control valves between any part of the PU and the engine intake air is forbidden."
These rules have prompted teams to fit piping to feed oil vapour out of the backs of their cars, which was causing the smoke in testing.
Ferrari has elected to pipe its vapour through a channel built into the lower part of its crash structure casing.
This, paired with what appears to be much more oil vapour being dispensed by the engine than other teams, resulted in the distinctive vapour trail.
The very cold conditions increased the visibility of the warm oil vapour too, and on track it would have been exaggerated by air flowing around the crash structure and through the diffuser.
Other teams opted to place their pipework either alongside their exhaust, most likely following recommendations from their engine suppliers, or to have it venting to the atmosphere from other locations.
It is not yet clear whether the smoking characteristic has caused any concern for Ferrari or if the design will be tweaked ahead of the Australian Grand Prix.
Although the smoke looked dramatic, the FIA does not feel it need to interfere because it is not appearing on the circuit.
F1 race director Charlie Whiting suggested the characteristic was similar to what happened with Toro Rosso on occasion last year on the grid.
"We see it quite often, we saw it a lot with the Toro Rosso last year whenever they fired up," Whiting told Autosport.
"We think that's just oil getting into the turbo through the seals. It's not doing it on the track."