The Subaru 6-Speed (WRX STI 2007–18) is a six-speed manual gearbox.
First gear is 3.636:1 and 6th is 0.756:1. Divide one by the other and the overall spread is 4.81:1. That is a wide spread: a short first to get the car moving and a tall top to bring cruise revs down.
6th is an overdrive at 0.756:1: the output shaft turns faster than the input shaft. Two of the six gears are overdrives. No gear is exactly 1.00:1, so there is no direct drive.
The biggest step is 1st to 2nd, where the ratio drops 39%. The smallest is 4th to 5th at 15%. On each upshift the revs drop by the same percentage as the ratio.
The final drive lives in a separate diff, so the speed table shows three common ratios: 3.42, 3.73 and 4.10. With a 3.73 final drive and 225/45R17 tyres, 6th at 6,000 rpm works out at 254 km/h (158 mph), and first runs out at 53 km/h (33 mph). That is how tall the gear is, not a top speed. Drag and power decide that. At 70 mph in 6th the engine turns about 2,660 rpm.
Nearly the same box as the Subaru 6-Speed (Impreza WRX STI 2004–06): 2nd is 2.235 here and 2.375 there; 3rd is 1.521 here and 1.761 there; 4th is 1.137 here and 1.346 there. That page is the one listed for search; this one stays for anyone after this exact version.
Ratios
| Gear | Ratio | Step |
|---|---|---|
| 1st | 3.636:1 | - |
| 2nd | 2.235:1 | 38.5% |
| 3rd | 1.521:1 | 31.9% |
| 4th | 1.137:1 | 25.2% |
| 5th | 0.971:1 | 14.6% |
| 6th | 0.756:1 | 22.1% |