What is the diff ratio for a 2013 WRX?
The diff ratio for a 2013 Subaru WRX is 3.90:1 for most US-market cars with the six-speed manual transmission.
In automotive terms, the diff ratio (final drive) describes the gear reduction between the transmission and the wheels. It determines how many engine RPMs you get per wheel rotation, affecting highway cruising RPM, acceleration feel, and overall gearing. While 3.90:1 is the common figure for the 2013 WRX, regional variations can exist, so it’s worth checking your specific vehicle’s documentation if you need an exact number for tuning or trip planning.
Understanding what the final-drive ratio means for performance
The final-drive ratio is the last stage of gearing before the wheels. A higher numerical ratio (larger number) lowers engine RPM at a given speed, which can improve fuel economy on long highway trips and smooth out cruising, but may soften off-the-line acceleration. A lower numerical ratio (smaller number) increases engine RPM at the same speed, which can improve initial acceleration but raise cruising RPM. For the 2013 WRX, the 3.90:1 final drive is chosen to balance spirited acceleration with reasonable highway comfort.
2013 WRX specifics by market
Subaru’s global lineup sometimes used different final-drive numbers depending on market, transmission, and production run. In the United States, the 2013 WRX with the six-speed manual commonly lists a final-drive ratio of 3.90:1. If you own a non-US model or a car with a different gearbox, check the exact specification through official documentation or your VIN build data.
To verify your car's exact final-drive ratio, use these common methods:
- Check the owner's manual or the service manual for drivetrain specifications.
- Inspect the differential housing for a tag or stamping that includes the final-drive number.
- Use the VIN to retrieve the build sheet or factory specifications via a Subaru dealer or official portal.
- Ask a dealer or Subaru technician to confirm the final-drive data from production records for your exact VIN.
Knowing the exact final-drive ratio helps with gear calculations for tuning, correcting speedometer error after tire changes, and planning trips where precise RPM at highway speeds matters.
Summary
The 2013 WRX’s final-drive ratio is commonly 3.90:1 for US-market six-speed manual cars. Always verify for your exact vehicle via the manual, differential tag, VIN build sheet, or dealer data to account for regional or production variations. Understanding the ratio aids in predicting performance, fuel economy at speed, and maintenance planning.
Does the Subaru WRX have a limited slip differential?
No, the standard Subaru WRX (since 2015, for example) does not come with a mechanical limited slip differential (LSD) from the factory; instead, it uses an electronic system to simulate an LSD effect. However, older WRX models did have a rear viscous LSD, and the high-performance STI version has mechanical LSDs in both the front and rear. It is possible to add an aftermarket mechanical LSD to a standard WRX.
Standard WRX
- No mechanical LSD: Newer standard WRX models typically lack a mechanical LSD, using an electronic torque-vectoring system that applies the brakes to simulate the effect of an LSD.
- Aftermarket upgrade: You can install an aftermarket mechanical LSD, which can be a popular modification for improved traction and handling, especially in performance driving or autocross situations.
WRX STI
- Mechanical LSDs: The WRX STI comes equipped with a mechanical all-wheel-drive system that includes both front and rear mechanical LSDs.
- Driver-adjustable: The STI features a Driver-Controlled Center Differential (DCCD) that allows drivers to adjust the torque split for different conditions.
What is the specs of the 2013 WRX?
The 2013 Subaru WRX features a 2.5-liter turbocharged flat-4 engine with 265 horsepower and 244 lb-ft of torque, paired with a 5-speed manual transmission and Symmetrical All-Wheel Drive. Standard features include a sport-tuned suspension, 17-inch alloy wheels, and a hood scoop. The WRX STI model upgrades to a 305-hp engine, a 6-speed manual transmission, Brembo brakes, and a more performance-oriented suspension.
This video provides a review of the modified 2013 Subaru WRX, showcasing its performance and modifications: 59sMaxSpeedMikeYouTube · Jul 23, 2020
Engine and performance
- Engine: 2.5L turbocharged flat-4
- Horsepower: 265 hp @ 6000 rpm
- Torque: 244 lb-ft @ 4000 rpm
- Transmission: 5-speed manual
- Drivetrain: Symmetrical All-Wheel Drive
WRX STI model upgrades
- Horsepower: 305 hp @ 6000 rpm
- Torque: 290 lb-ft @ 4000 rpm
- Transmission: 6-speed manual
- Brakes: Brembo four-piston front and two-piston rear calipers
- Suspension: Firmer, more performance-oriented than the standard WRX
You can watch this video to learn about the specifications of the 2013 Subaru WRX STI 5-Door: 1mMatt Maran MotoringYouTube · Mar 31, 2014
Exterior and interior
- Wheels: 17-inch alloy wheels on standard WRX, 18-inch alloy wheels on STI
- Other features: Functional hood scoop on the standard WRX
- Cargo space: 11.3 cu.ft. for the sedan
This video reviews the 2013 Subaru WRX, discussing its features and performance: 1mMatt Maran MotoringYouTube · Nov 20, 2013
Fuel economy and dimensions
- Fuel economy: 21 mpg combined (19 mpg city / 25 mpg highway)
- Fuel type: Premium unleaded gasoline (required)
- Wheelbase: 103.3 inches
- Curb weight: Approximately 3,208–3,417 lbs depending on model
How do I tell what my diff ratio is?
And count your drive shaft turns. Okay so here we go you can see that I've got two pieces of tape with a little white chalk mark. So you can see it very clearly on the underside of the car.
What is the rear diff ratio for a 2013 WRX?
2008-2014 Subaru Impreza WRX Turbo Rear Axle Differential Carrier 3.90 Ratio.
