Subaru WRX STI 2009 | Specs, Performance & What Sets It Apart

The 2009 Subaru WRX STI delivers 305 horsepower from its turbocharged 2.5L boxer engine, pairing a 6-speed manual with full-time AWD for a pure performance driving experience.

For the full breakdown, see our best 09 Subaru Wrx Sti guide.

The 2009 Subaru Impreza WRX STI marked a meaningful upgrade over the 2008 model, with a 25-horsepower gain that brought it to 305 hp. This 5-door hatchback combined Subaru’s sturdiest drivetrain components with a turbocharged boxer engine, creating one of the most practical performance cars of its era. Here is everything the specs reveal.

How Much Horsepower Does The 2009 WRX STI Make?

The 2009 STI is powered by Subaru’s EJ257 engine, a 2.5-liter DOHC turbocharged flat-four with variable valve timing and an intercooled high-boost turbocharger. Output measures 305 horsepower at 6,000 rpm and 290 lb-ft of torque at 4,000 rpm. The horizontally opposed boxer layout keeps the center of gravity low, aiding cornering stability, while the 8.2:1 compression ratio supports the turbocharger’s boost pressure without detonation — provided you feed it the right fuel.

Subaru mandates premium unleaded gasoline with a minimum of 91 octane. Using regular fuel risks engine damage in this high-boost application; 93 octane is recommended for full performance and knock protection. Performance estimates place the 0–60 mph sprint at approximately 4.8 seconds and the quarter mile at 13.5 seconds at 101 mph, with a theoretical top speed of 157 mph.

The 2008 model year STI produced only 280 hp, so the 2009 represents a genuine step forward. The standard WRX also received a power increase to 265 hp in 2009, narrowing the gap between the two models while keeping the STI clearly ahead.

Drivetrain, Transmission and Dimensions

The STI is exclusively a 6-speed manual car in the US — no automatic was offered. The close-ratio 6MT includes Subaru’s Hill Holder system, which automatically prevents rollback on inclines when the clutch is released. The shift action is notched and mechanical, rewarding deliberate inputs rather than rushed shifts. Power is distributed through Subaru’s Symmetrical Full-Time AWD system, built around a Multi-mode Driver Controlled Centre Differential (DCCD). The driver can adjust the DCCD between Auto and Lock modes to suit conditions — Auto adjusts torque split dynamically based on grip, while Lock fixes a 50:50 split for maximum traction in low-grip situations like snow or loose gravel. Helical limited-slip differentials at the front and a TORSEN unit at the rear complete the package.

The 2009 STI hatchback weighs 3,395 pounds and stretches 173.8 inches long on a 103.3-inch wheelbase. It is 70.7 inches wide and 58.1 inches tall with 6.1 inches of ground clearance. Factory tires are 245/40 R18 mounted on 18-inch wheels. Fuel capacity is 16.0 gallons.

Pricing, Fuel Economy and Common Confusions

Fuel economy — 17 mpg city, 23 mpg highway, 20 mpg combined — reflects the turbocharged engine’s thirst under boost. The 16-gallon tank gives a practical range of roughly 300 miles on the highway, though real-world mixed driving typically lands in the low 20s while spirited driving pulls it lower.

Several details commonly confuse buyers researching this generation. The 2009 model launched in mid-2008, so a car with an early 2008 registration date may actually be the 280-horsepower 2008 model. The STI was offered only as a 5-door hatchback in the US; the sedan body style was exclusive to the standard WRX that year. Global-market variants such as the Spec C and A-Line were never sold in the US, so references to them do not apply to an American-market car. And while the WRX received a 265-hp engine in 2009, the two models remain distinct — the STI retains the 6-speed manual, DCCD, and upgraded differentials that define its performance character. Understanding these distinctions is critical before making a purchase decision.

For anyone shopping this generation, checking our roundup of current listings for the 2009 WRX STI can help you compare options and find a well-maintained example. The STI’s mechanical complexity — particularly the DCCD system, turbocharger, and limited-slip differentials — rewards a thorough pre-purchase inspection. The factory warranty covered 36 months or 36,000 miles. The vehicle is LEV2 emissions certified for all 50 states.

FAQs

Is the 2009 WRX STI a hatchback or sedan in the US?

The 2009 WRX STI is exclusively a 5-door hatchback in the United States. Subaru offered a sedan body style for the standard WRX that year, but the STI was hatchback-only in the US market.

What octane fuel does the 2009 STI require?

Subaru mandates premium unleaded gasoline with at least 91 octane for the 2009 STI. Using regular fuel can cause engine damage due to the turbocharger and 8.2:1 compression ratio. 93 octane is recommended for best performance and detonation protection.

How is the 2009 STI different from the 2008 model?

The 2009 model received a power increase from 280 hp to 305 hp, making it significantly stronger than the 2008 version. The 2009 model also launched in mid-2008, so early registrations may be the lower-output 2008 car.