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Why Subaru needs to put a dual-clutch transmission in the STI
November 12, 2019
The Subaru WRX STI has been a staple in the performance car market, at track days, and race tracks for years. There are a number of reasons for that, but one that maybe doesn’t get as much attention as it should is the STI’s drivetrain. The STI has the most durable drivetrain that Subaru makes, and there really is almost no weak link in the transmission, differentials, etc. If you are building a car to make power and perform at the track reliably, having a solid drivetrain in the car is definitely a requirement, and the STI has that for sure.
At this point, the STI drivetrain has remained largely unchanged since the car first arrived it the US market in 2004. Starting in 2015, there are more electronic aids such as yaw control, but the fundamental design of the STI 6-speed transmission and Driver Controlled Center Differential (DCCD) have only seen minor changes in the last 15 years. The very capable combination of differentials in the STI (front, center, and rear), and the fact that the transmission has proven reliable time and again up to 600 wheel hp an above completely stock the STI’s drive train one of the most reliable and best performing options in its class. It is the bedrock that the car is built on, and really it would make sense that Subaru wouldn’t want to change anything.
While I think that there should always be an STI available with its tried, tested, and proven 6-speed, it is now time for Subaru to give us another option. Subaru needs to put a dual-clutch transmission in the STI, ideally as an option for the up coming 2021 revision of the car.
The simplest reason for this is because people have been wanting a dual-clutch/sequential transmission in the STI for while now. A decade ago, that was an expensive and exotic option, now, dual clutch transmission are almost becoming an common option. If you look at the way that the market is changing, and the cars that the STI is now competing with, Subaru is now taking a much more substantial risk by not giving us a Dual Clutch Transmission. Manual transmissions are now such a small percentage of cars that are sold that there is now a significant number of people that don’t know how to drive a manual transmission. And this is more true the younger the demographic you are looking at gets.
Right now, Subaru offers the Impreza, BRZ, WRX, and of course the STI in a manual transmission, and that makes up about 10% of the total number of new cars that you can even find now with a manual transmission. There was a recent article that said that only 1.6% of cars sold in the 3rd quarter of 2019 had a manual transmission, and that is a spooky statistic if your flag ship car that is branded as a daily driveable sports car for the masses but it has only one option for its transmission.
There is also the fact that a Dual Clutch/Sequential gives you a competitive advantage. Subaru knows this of course, which is why all of the Subaru Rally cars and Subaru GRC cars run sequential transmissions. What is interesting is that cars that offer Dual Clutch transmissions are becoming common enough now that some racing classes, like Track Modified in Global Time Attack and Grid Life, are now allowing you to put in a sequential transmission if your car didn't come with one stock. This is leading an increasing number of people running Subaru's to consider installing a sequential because they feel they need to in order to stay competitive in their class.
Putting a DCT/DSG transmission into a car that didn't come with it from the factory is expensive, and then getting the car to work properly with the new sequential, and to keep the car and the transmission running reliably is also more difficult. If Subaru doesn't give us the option of a DCT/DSG transmission from the factory, it is possible that this alone will push more people away from using a Subaru to compete because they would be up against cars that come with this option.
Considering that the STI is getting a complete re-design in 2021, that is the time to introduce this option. Even if the Dual-Clutch adds $5,000 to the base price of the STI, it would absolutely be worth it. The STI needs that as much as it needs a bump in power to get it back on top of its class.
With any luck, Subaru is well ahead of us, and they are just waiting to blow us away with the new STI.
- Jon Cooley