It is widely accepted that the higher the speed, the higher the role aero plays in its performance. Based on that, the results of the fastest stages should be interesting to analyze, in order to determine whether they have any relationship with the quality of the aero balance of the WRC cars. So, why don’t we take a look at them?
The starting point is the result of all special stages developed in the last 12 months, from Rally Turkey 2018 to Rally Deutschland 2019. During a 12 month period, we can ensure that all type of surfaces and events are included. The results are all included in the table below.
Table 1. Stage wins by car and surface, in the period between Rally Turkey 2018 and Rally Deutschland 2019.
During the last 12 months, the Toyota Yaris WRC has been the top performer team in the special stages, as they have won 131 of the 268 stages that were run. Their win percentage is also the highest, even when a correction is applied to normalize the number of cars included in each event. The reason behind such normalization is that teams as Citroën aligns only two cars, Toyota and Hyundai three cars per event, and Ford two or three, depending on the event. So, the corrected percentage eliminates this factor, in order to allow a fair comparison. These results will be used for comparative purposes all over the post, as a reference.
Some other interesting conclusions can already be drawn from table 1, apart from Toyota leadership in this field:
Hyundai is the second best team…except on snow (Sweden), where their results are well below average
Citroën and Ford have performed similarly, according to corrected percentage.
Do these results are similar when considering only the fastest stages, where aero is supposed to play a more important role? The answer can be found in table 2. We consider the fastest stages those where the average speed is higher than 110 km/h. It is true that average speed should be accompanied by other factors (basically the number of fast and slow corners, long straights,…) but this information is not easily available, so we depend on average speed.
During the period considered, there were 64 special stages with such average speed (>110 km/h), with the Rally Finland 2019 SS10 (Äänekoski 2) as the top of the fastest stages. There, Kris Meeke and Seb Marshall together with Jari Matti Latvala and Mikka Anttila were able to drive their Toyota Yaris WRC at an average of 131,8 km/h.
Table 2. Stage wins by car and surface, in the fastest stages (average speed >110 km/h) from the period between Rally Turkey 2018 and Rally Deutschland 2019.
Some interesting details can be noted in table 2:
- Toyota performance is better at the fastest stages (41% stage wins) than the 12 months average, at any speed (33%); this result is confirmed in all three surfaces,
- Ford and, to a lesser extent Citroën, also performs better at the fastest stages; Ford obtains a win in 14% of fastest stages, versus a 9% in all type stages, while Citroën gets a 13% in the fastest stages versus an average of a 10%
- the Fiesta performs really well on snowy fastest stages, while the C3 gets its best results on gravel
- Hyundai results at fast stages are very far from their average, as they win only in a 6% of the fastest stages, versus a year average of 30% wins; this is especially true in snow, and also confirmed on gravel.
Do these results by itself can give us some indication about the aerodynamic quality of the cars? It is true that, to reach such high average speeds, a good aero balance is required. Results confirm then that the aero balance of the Yaris is really good.
T.Suninen/M.Salminen, Ford Fiesta WRC, Rally Sweden 2019, 23rd – picture by Tapio Lehtonen – rallirinki.net
According to the results, Ford aero balance has to be also remarkable, as shown by the results they obtained in the fast snowy stages of Rally Sweden 2019.
On the contrary, the fact that Hyundai results at high-speed stages are far below from the 12 months average, is not necessarily due to a poor aero balance. There are many other reasons that could justify this.
In addition, it is worth to remember that Hyundai made some modifications in their frontal aero package before Rally Finland. A review of their results before and after such modifications can help to determine whether their performance has improved or not.
Table 3. Stage wins obtained by the two aero configurations of the Hyundai i20 Coupé WRC: before Rally Finland 2019 (named v2018) and since Rally Finland 2019 (named v2019) in the fastest stages (average speed <110 km/h) from the period between Rally Turkey 2018 and Rally Deutschland 2019.
T.Neuville/N.Gilsoul, Hyundai i20 Coupé WRC, Rallye Deutschland 2019, 4th – picture by Hyundai Motorsport
A more detailed analysis of Hyundai results (table 3) seems to confirm the benefits of the new front aero package: of the four stage wins obtained by Hyundai in this period in the fastest stages, only 1 stage win was obtained with the old aero configuration (SS15 Rally Chile 2019, by Seb Loeb/Daniel Elena) while the other three were obtained by Andreas Mikkelsen and Andrea Jaeger in Rally Finland 2019. And a further confirmation comes from the fact that Hyundai did not obtain any stage win in the 2018 edition of the Finnish rally, against 3 in the current year edition.
So the only conclusion we can draw for Hyundai is that the new aero package has contributed to improving the car performance, while still other factors (not necessarily aero) prevent them from performing better at the fastest stages.
The Hyundai low percentage of wins at fast stages means that they have to compensate it at lower speeds, as they are the second best team according to the 12 months average results (table 1). Where do they balance this situation? Table 4 has the answer.
Table 4. Stage wins by car, surface and average speed from the period between Rally Turkey 2018 and Rally Deutschland 2019.
Table 4 shows how Hyundai performs almost as well as Toyota in the medium speed stages (90-110 km/h) on tarmac, and even better than the Toyotas in the low speed gravel stages (<90 km/h). These results contribute to place Hyundai as the second best performer in the average results of the period evaluated.
E.Lappi/J.Ferm, Citroën C3 WRC, Rally Finland 2019, 2nd – picture by Henri Vuorinen Photography
Results also show that the Citroën C3 WRC performs better at gravel medium speed stages, while the Fiesta WRC is better at low speed gravel stages.
What is the relationship between these results and aero performance? At medium and low average speed stages is difficult to establish. At these speeds, the role of the aero is less important than at higher speeds, while many other factors play an increasingly significative role. The only way to establish clear trends is by having all the info at hand, something that is only available to teams. So, if any of these results can be helpful for any of the teams, we will be more than satisfied.
In summary, the main conclusions drawn from our analysis are:
- the Toyota Yaris WRC is clearly the best in setting the fastest time in the special stage results of the period analyzed, (131 wins out of 268)
- Hyundai is the second best team…except on snow, where their results are well below average
- Toyota performance is even better at the fastest stages (41% versus 33% in the 12 months average); this is confirmed in all three surfaces,
- these results confirm that the aero balance of the Yaris WRC is really good
- Ford and, to a lesser extent Citroën, also perform better than average at the fastest stages;
- the Fiesta WRC performs really well on fastest snow stages, while the C3 WRC gets its best results on fastest gravel stages
- Hyundai i20 WRC results at the fastest stages are well below their average, as they got only wins in a 6% of stages, versus a year average of 30% wins; this is especially true in snow, and also on gravel.
- Results show that Hyundai’s new aero package has contributed to improving the car performance, but still, other factors (not necessarily aero) prevent them from performing better at the fastest stages.
- At medium speed stages, Toyota and Hyundai performs at the same level on tarmac, while Hyundai is the best performer on gravel slow stages
Finally, the answer to the question in the title of the post remains open: good results at the fast speed stages surely require a good aero balance, while at medium and low speeds the relationship is difficult to establish with the information available. In any case, the results show the behaviour of the cars at different speeds and surfaces, which is always interesting.
This post includes opinions of the author, which are certainly not always right. If you detect any error or you disagree, do not hesitate to contact us, by sending an email to firstname.lastname@example.org. We love to learn!