https://www.amazon.com/Pedal-Commander-throttle-controller-Crosstrek/dp/B078JHYM7V?ref_=ast_sto_dp

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It is a simple computer program that over rides the pedal response. Has nothing to do with the engine. Normally there is a bit of a delay when pressing the gas pedal down and your car moving. With this easy to install device, you can choose between 4 modes. Eco, City, Sport and Sport+ with 8 degrees of variation between each level. You will be surprised at the quick and sharp responsiveness of the sportier modes. It's like an entire new car. These modes eat up more gas and does not actually increase your horse power.

With gas prices these days i only running in eco -4 mode to save as much gas as possible. I save maybe 3 mpg per tank. Which adds up over the entire year. While it is said that this commander doesn't mess with your engine or transmission at all, YOU'LL WANT TO TAKE IT OFF DURING SUBARU DEALERSHIP SERVICES as they look for any reason to not have to void your warranty.

I have saved around $100 in the first year of owning the device running primarily in eco mode. Soon it will pay itself off being that it is $300. I only use sport mode when i need to merge aggressively or just trying to have a little fun.

It comes with a nice phone application and with my phone mounted on my E-brake handle with a bicycle mount, i can have it open and change it from situation to situation very easily even without diverting my eyes from the road.