VW Polo WRC: aerodynamics of the great absent in 2017 versus competitors

Now that VW has initiated tests for the Polo GTI R5, it is worth to review the design of the Polo WRC 2017 and to compare it with the current generation of WRC, once they have completed their first season.

It was the beginning of November 2016 when Volkswagen Motorsport announced their withdrawal from WRC, for what the promising Polo WRC 2017 would never have the chance to prove his value. It didn’t matter it was the team that had completed the longest and most complete test program, all their efforts were suddenly thrown away.

After that decision, the team still worked on the car to get it homologated, but not all modifications tested were included in the latest tests, once the decision was public, or even in the unit Raimund Baumschlager has been driving this year in the Austrian Rally Championship.

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S.Ogier/J.Ingrassia, VW Polo WRC 2017, test in Gratallops, September 22, 2016

For this review, we will use the pictures taken by the author in the test carried out in the first kilometers of a typical Rally Catalunya stage, in September 2016. This is the last configuration of the car seen in tests, which was also used in gravel tests in Wales later in October 2016, with the only visible modification of a more prominent front splitter.

VW Polo front splitter (A) shows an elevated central part, probably designed to reduce damage on splitter on rough terrains and while cutting corners on tarmac stages. This is the first difference with respect to all other WRC, as all of them use flat splitters. Only Citroen used a splitter with an elevation on the upper central area in Montecarlo Rally 2017.

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Citroën C3 WRC, Montecarlo Rally 2017 – picture by Vladislav Maschl for rally-mania.cz

No dive planes were designed by VW, but side panels (B) were introduced at both sides of the front bumper to help to channel the airflow to the sides of the car, similar but bigger to those present in the Toyota Yaris WRC and the Ford Fiesta WRC 2017.

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The size of the air inlet (C) for cooling the engine bay was increased versus the Polo WRC 2016, while specific air inlets for brake cooling were added on both sides (D). Two vents of significant size were allocated on both sides of the bonnet for hot air removal (E).

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Air inlet for rear brakes cooling (F) was located in the rear wheel arch, which incorporated a small lip on top (H). This solution has been also incorporated by Hyundai in the set of modifications introduced in the i20 Coupé WRC in the latest part of the 2017 season (explained here).

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T.Neuville/N.Gilsoul, Hyundai i20 Coupé WRC, Wales Rally 2017, 2nd

The front wheel arches incorporated a side lip (G), designed to help to channel airflow to the sides of the car. Hyundai i20 Coupé WRC included also similar lip since January 2017.

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D.Sordo/M.Martí, Hyundai i20 Coupé WRC, Montecarlo Rally 2017, 4th -picture by Martn Husár – ewrc-results.com

Also, the size and shape of the front and rear wheel arches of the Polo WRC are very similar to that of the Hyundai i20 Coupe WRC. Air outlets from brakes were located in the rear part of the front (I) and rear (J) wheel arches, as well as in the rear bumper (K). No louvres were included in any of them, to redirect airflow into any specific direction.

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A cut (L) to help side airflow was introduced in the lower part of the doors, similar to most of the other 2017 WRC. Also, big side skirts (M) were used, all over the sides of the car, to prevent air from entering below the car to disturb underbody airflow.

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The rear diffuser of the Polo WRC 2017 seems less developed than that designed by the other teams, which might be an indication that was not the definitive design. Even so, it included four vertical streaks, to facilitate a less turbulent flow at the car exit. The angle of the diffuser was very high, and with no change of angle, as most of the other teams have, except Hyundai’s diffuser.

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D.Sordo/M.Martí, Hyundai i20 Coupé WRC, Rally Catalunya 2017, 15th

The rear wing followed a similar configuration to that of Hyundai i20 Coupé WRC, that is, swan-neck supports (O), an upper plate with a significant angle of attack (P), open endplates (R) and a lower plate with Gurney flaps (S).

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A.Mikkelsen/A.Jaeger, Hyundai i20 Coupé WRC, Rally Catalunya pre-event test, September 2017

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As shown by the images above, the most similar car, in terms of aero design, to VW Polo WRC is the Hyundai i20 Coupé WRC (see this video to confirm), although certain solutions proposed by the German team can also be found in the other three cars that have taken part in the 2017 season. The only man having driven consistently both cars up to now, Andreas Mikkelsen, recently confirmed such similarity in an interview by Motorsport News.

Final tests were conducted in Sweden in November 2016 with Marcus Gronhölm and Dieter Depping, from where the car should be ready for homologation. But VW missed the deadline of January 1st, 2017, and later efforts to homologate it were fruitless, as FIA stated in February the car was not eligible to compete in any of the events in the 2017 World Rally Championship (WRC) calendar.

The design of the VW Polo WRC 2017 was, as VW technical director Francois-Xavier Demaison declared in December 2016 to Autosport, relatively conservative compared to rivals, although he expected to have been tougher, especially in rough terrains. They preferred reliability to pure aero performance because they “thought it would be better to keep good downforce for the whole loop rather than have great downforce for five kilometers then nothing for the rest”.

The lack of dive planes and the simplicity of the rear diffuser confirm the conservative approach claimed by Demaison, but it is also true that many of the solutions included in the VW Polo were also used by the other teams.

What we will never know is how well it would have performed against its rivals in the 2017 Championship.

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