!NEW! Outstanding Aerodynamics: Best Conditions for the Opel Astra TCR

• Efficient aerodynamics are one of the keys to success in touring car racing
• Meticulous wind tunnel work important element of vehicle development
• Already excellent aerodynamics of serial production Astra as the perfect base

Key to success: Aerodynamic efficiency is the result of a well-balanced ratio of downforce and drag. 

Aerodynamics have become increasingly important in motorsports. In the past, aerodynamic problems have often been hidden by simply increasing engine performance. However, the key to success in modern motorsports is now the same as in serial production: efficiency. This was one of the most important development goals for the Opel Astra TCR that was created to compete in the Touring Car Racer Series (TCR).

New Opel Astra TCR: Wind tunnel testing for efficient aerodynamics.

Aerodynamic efficiency is the result of a well-balanced ratio of downforce and drag. In order to achieve the perfect combination of high speeds through the corners and on the straights, engineers strive to have as much as possible downforce while simultaneously reducing drag as far as possible. The new Astra comes with the perfect prerequisites for a close to serial production touring car. The “Car of the Year 2016” has an outstanding drag coefficient for hatchbacks of 0.272. It therefore is perfectly suited to serve as the base for a fast racing car.

Compared to its serial production sibling the width of the Opel Astra TCR has been increased to 1,950 millimeters – the maximum permitted by the rules. The bumpers, fenders and side panels have also been modified. The front splitter and the rear wing are the main elements creating the decisive downforce. Both features have been defined as standard components in the TCR regulations to keep costs down. Manufacturers can thus not change the shape or finish but they can fine-tune the mounting position. The location of the rear wing is especially important. According to the regulations, the rear wing is not allowed to protrude the roofline. Furthermore, it is not allowed to protrude by more than 1,050 millimeters – measured from the center of the rear wheel hub.

Increased width: The front splitter and the rear wing are the main elements creating the decisive downforce.

The downforce created by the rear wing increases the more it stands in the wind. However, this simultaneously increases drag, which is detrimental for top speed. Therefore, a compromise between drag and downforce needs to be found. The same goes for the setting angle of the front splitter. It needs to be as flat as possible while being steep enough to the keep the front axle stable when braking and to prevent understeer in the corners. Once again the aerodynamic balance in decisive, i.e. the downforce ratio between front and rear axle. This ratio needs to be well balanced so that the car remains stable no matter what the driving situation.

Meticulous preparation: Wind tunnel work about the position of the rear wing, the angle of the front splitter and the design of the fenders and the side sills.

In order to get as close to this delicate balance as possible from the very start, the development team around Opel Motorsport’s Senior Manager Dietmar Metrich put the Astra TCR through an aerodynamics test lasting several days. The team decided to use the wind tunnel of Stuttgart University for the tests. “It has a rolling floor and can simulate speeds of up to 250 km/h. That makes it ideal for our purposes,” explains Metrich.

Time in the wind tunnel is expensive and therefore calls for meticulous preparation. “We used models to prepare various solutions. This gave us to chance to test and change the configurations when we were on site,” says Metrich. “It was mainly about the position of the rear wing, the angle of the front splitter and the design of the fenders and the side sills.”

Dietmar Metrich suddenly turns very quiet when it comes to communicating data and measurements. “I can tell you this much: we feel perfectly prepared thanks to the excellent suitability of the base model. We will only find out where we stand when the cars compete on the race track but that makes the whole thing really exciting!”

!NEW! All-New Opel Astra K: Outstanding Aerodynamics for Best Efficiency

• Most streamlined Astra ever: exemplary drag coefficient of 0.285
• Clever design: more compact dimensions reduce drag
• Attention to detail: rear spoiler, C-pillar and underbody optimized
• Increased efficiency: great aerodynamics meet latest generation engines 

Increase in efficiency: All-New Opel Astra K – great aerodynamics meet latest generation engines.

Lighter, more frugal and more agile – the new Opel Astra K represents a quantum leap in the development and targets maximum efficiency. Its design and vehicle architecture also set standards in aerodynamics and continue a traditional Opel strength – when the Kadett E GSi was introduced in 1984 it was the most streamlined hatchback in the world with a cd value of 0.30. Outstanding aerodynamics are closely linked to economical fuel consumption and climate-friendly CO2-emissions – another long-time Opel strength.

Most streamlined Astra ever: Exemplary drag coefficient of 0.285.

A decisive advantage of the new Astra is that it is much more compact than its predecessor is. It is around 2.5 centimeters lower and 0.5 centimeters slimmer, including the more slender wheels. But to make the vehicle as streamlined as possible, precision and attention to detail were also necessary. The engineers paid special attention to the roofline, the C-pillar and the construction of the underbody. The result speaks for itself: the new compact class Opel is amongst the elite of the most streamlined models in its class with a drag coefficient of 0.285.

In perfect shape: Opel engineers paid special attention to the roofline, the C-pillar and the construction of the underbody of the new Astra K.

“We have made the new Astra more aerodynamic than ever before. The drag coefficient values beat the best values achieved by its predecessor across the board. We gained some important knowledge from the tests we conducted in the ultra-modern wind tunnel of Stuttgart University who we have been working with for many years,” said Reiner Weidemann, Head of the Opel Aerodynamics department. “This helped us make the new Astra the most streamlined compact class car ever produced by Opel.”

Design and vehicle architecture: setting standards in aerodynamics

Clever design: The engineers decided to let the roof of the new Opel Astra K flow out gently to the rear to avoid any drag.

Leaner, smarter and more innovative than ever before – the new Astra epitomizes highest efficiency and demonstrates the next evolutionary stage of Opel’s design philosophy “Sculptural artistry meets German precision”. From an aerodynamics point of view, this means: the new Astra has a drag coefficient of 0.285 with its athletic and dynamic appearance along with the numerous measures taken above and under the outer shell. The new Astra has a total length of 4.37 meters and is roughly five centimeters shorter than its predecessor is. The height has been reduced by 2.5 centimeters to 1.48 meters and the width reduced by 0.5 centimeters to 1.81 meters. These dimensions also have a positive impact on the overall drag, with a cross sectional area of around 0.642 square meters (compared to 0.770 square meters for its predecessor), and thus on fuel efficiency.

In the wind tunnel: The delicate rear spoiler serves as an effective separation edge that cuts the airflow at the top without creating any disturbing wake turbulences.

However, the art of the exemplary aerodynamic performance is down to attention to detail. The engineers decided to let the roof flow out gently to the rear to avoid any drag. The delicate rear spoiler serves as an effective separation edge that cuts the airflow at the top without creating any disturbing wake turbulences. Even the C-pillar with its small edges was designed to split airflow more efficiently than was the case for the previous Astra, thus reducing drag.

Attention to detail: The Rear spoiler and the C-pillar of the new Opel Astra K have been optimized.

The engineers managed to achieve further improvements by overhauling the design of the underbody. Opposed to many competitors, Opel specifically decided not to look to a full underbody paneling. Instead, all parts were examined and reworked to ensure better airflow. The underside of the car now has airflow-optimized structures and battery attachment, the new rear axle now sits higher compared to the previous Astra, thus no longer providing an obstacle for the air flowing under the car. These measures all play a key part in the exemplary aerodynamics. Expressed in cold figures, the most eco-friendly version of the previous Opel Astra had a drag coefficient of 0.325. The basic version of the all-new Opel Astra has an outstanding drag coefficient of 0.285. Even the automatic diesel of the new generation with 18 inch wheels easily beats the most streamlined version of the predecessor with a drag coefficient of around 0.31. And that is not all – an even more aerodynamic and frugal ecoFlex version is planned for the future.

Double efficiency: improved aerodynamics meet latest generation engines

The conscious decision not to use a full underbody paneling also means less weight and consequently lower fuel consumption along with reduced production costs. Advantages that have a positive impact on the price – something that can be passed on to the customer.

Combined with the fact that every new Opel Astra will be propelled by an engine of the latest generation with outputs ranging from 70 kW/95 hp to 147 kW/200 hp customers can look forward to a win-win-win situation. All of the new generation engines combine strong performance and economical fuel consumption with outstanding responsiveness while at the same time offering smoothness and low noise levels. For example, with the 1.0 liter turbo and Easytronic 3.0 the new Opel Astra is the most fuel-efficient and eco-friendly gasoline-engined car in its class (4.2 l/100 km in the combined cycle, 96 g CO2/km). That is efficiency à la Astra.