F1's looming fuel crisis

Testing in Barcelona revealed a potential Ferrari weakness that could lead to Mercedes dominating once again

Regardless of what pre-season testing did or didn’t tell us about the competitive order that was finally revealed in Melbourne, it highlighted something else that should concern us: at least one team – and maybe two – was unable to use its full performance in a race simulation because the 105kg fuel allocation wasn’t enough. That has some potentially negative competitive implications on the season ahead. Ferrari’s (and possibly Red Bull’s) struggle to maximise their performance potential within the fuel limit wasn’t expected to be a major factor around Albert Park or China, but come the more fuel-demanding circuits (Bahrain being one of them), it could potentially exaggerate a Mercedes advantage.

On the penultimate day of Barcelona testing Mercedes, Ferrari and Red Bull all did full race simulations with Valtteri Bottas, Sebastian Vettel and Max Verstappen respectively. They each completed more than 60 laps divided into three stints. Mercedes and Red Bull used medium tyres throughout (so not quite an exact race replica), Ferrari did the first stint on super-softs, the remainder on mediums. Because they had enough fuel on board at the start to complete a full race distance, we can know to a fair level of accuracy what the fuel load was on any given lap and therefore what the low-fuel equivalent would be for that lap. We can also derive an implied tyre degradation by comparing the fuel weight-corrected laps at the beginning and end of stints. Delving yet deeper into the numbers on the day, we can see an anomalous pattern with Vettel’s stints – in that there is only the tiniest amount of deviation from his average.

Putting numbers on it, the first medium-tyred stints of each driver (corrected for fuel weight) averaged as follows:

Bottas………………………………..1min 19.6sec
Vettel…………………………………1min 19.9sec
Verstappen………………………..1min 20.2sec

Around each average, what would normally be expected would be a pattern whereby as the driver pushed hard from the beginning of the stint to the end, the times would get progressively slower once the fuel correction was taken out, as the tyres’ grip steadily degraded. So there would be a fairly significant spread of fastest to slowest times around that average. This is the deviation.

Bottas’s stints show exactly this pattern and, taking his first stint, the deviation around that average of 1min 19.6sec comes out at 0.242sec (ie, that’s the average spread of his individual laps around that mean average). For Vettel (and to a lesser extent Verstappen) there is hardly any deviation evident, at 0.16sec and 0.18sec respectively. In other words, there is hardly any difference in their fuel-corrected laps from beginning of stint to the end 18 or more laps later. So either the Ferrari and Red Bull were incredibly kind to the tyre, allowing 18 laps to have hardly any effect on its performance… or Vettel and Verstappen were driving to a set lap time determined by their fuel allocation, guided by sector times updated on their dash at regular points through the lap. In such a case there would be little tyre degradation visible in the lap times because they would not be fully stressed.

Observers indeed reported Vettel apparently lifting and coasting his way into several of the corners on his race simulation. Suggesting it was indeed a fuel consumption issue – as did the fact that he suddenly found 1.5sec on the very last lap of his final stint, presumably when no longer needing to conserve. If so, that 1m 19.9sec average is a fuel-limited one. The problem seemed less severe for the Red Bull, but was still there. Significantly, such patterns were not visible on the other Ferrari and Renault-engined cars – suggesting that the greater grip of the SF71 and RB14 was allowing more full throttle, taking them over the fuel consumption threshold for that 105kg limitation. 

Barcelona has not traditionally been one of the most fuel-demanding tracks, typically sitting about halfway down that particular league table and well behind such as Austria, Singapore, Baku, Montréal, Sochi and Bahrain. The 105kg is the same for all tracks of course and difference in fuel demand from track to track has typically been expressed as either: a) more harvesting/less deployment for the more fuel-demanding tracks, ie boosting the electrical power more frequently, and using it more sparingly, thereby reducing average power over the lap or b) short-fuelling for the less fuel-demanding circuits, ie not putting in all of the permitted 105kg.

Should the full allocation of fuel not be enough, the driver will have to lift-and-coast to bring things back on schedule, coming early off the throttle and using the engine braking and drag to help more with the deceleration. In the 2014-16 seasons, we had tyres that couldn’t be pushed to anywhere near their maximum over a race stint – and so that reduced the fuel demand enough that the fuel limit was rarely, if ever, the limitation. Teams would short-fuel in the knowledge that the tyres would limit how hard the driver could push. Some lift and coast might be needed if the team had been over-zealous in its short-fuelling, but generally tyres dictated the pace, not fuel consumption.

Into 2017 with the faster cars and tougher, bigger, tyres, meaning a lot more full-throttle running, the fuel allocation was increased from 100 to 105kg to compensate. Short-fuelling, by necessity, became much less extreme. Mercedes continued to have the most efficient combination of power and fuel consumption and so the Merc-powered teams could short-fuel more than the others, but still 105kg proved just about enough everywhere not to tilt the playing field too much.

But something in Barcelona testing took the Ferrari past the threshold where 105kg was enough. The halo accounts for some extra weight and drag, both of which would punish fuel consumption. But probably of much more significance was the track’s resurfacing with a super-smooth and very grippy asphalt, following complaints from MotoGP riders. This has made the circuit significantly faster. Together with the usual strides in increasing downforce year on year, the cars are at full throttle longer and therefore use more fuel. For Mercedes this increase has not taken it over the threshold but for Ferrari and Red Bull it has.

What is currently unknown is how the resurfaced Barcelona compares with circuits traditionally heavier on fuel demand and therefore how many of the season’s races might be compromised by a dulled Ferrari and Red Bull challenge as the engines are turned down so as to eke out the fuel. How much of the ‘fuel crisis’ is the track resurfacing and how much the extra throttle that Ferrari’s and Red Bull’s extra downforce has made possible? Here’s hoping the Scuderia and Renault Sport can assuage that thirst.      

If it turns out that a significant number of races are going to be fuel-limited for Ferrari and Red Bull, allowing the Mercs to dominate against two cars that might otherwise be just as fast, might the regulations be tweaked? It would hardly be fair on Mercedes, but a fifth straight year of domination – and potentially seven – might make such measures inevitable.