Choosing the right ratio

This chart should assist you in selecting the right ratio for your road vehicle. Only popular models are covered. These ratios are suitable for road cars. As every track is different, it's best to contact Diff Lab regarding race ratios for your vehicle. For other vehicles, contact me if you need assistance.


BMW E30 - 318i / 318is Manual 5sp Better Fuel Economy: 3.46:1
Standard: 4.10:1
Faster: 4.27:1
Fastest: 4.45:1
BMW E36 - 323i / 325i / 328i Manual 5sp Better Fuel Economy: 2.93:1
Standard: 3.15:1 or 2.93:1
Faster: 3.46:1
Fastest: 3.64:1
BMW E30 - 320i / 323i / 325i Manual 5sp Better Fuel Economy: 3.07:1
Standard: 3.45:1, 3.64:1 or 3.73:1
Faster: 3.91:1
Fastest: 4.27:1
BMW E36 - 318i / 318is Better Fuel Economy: 3.07:1
Standard: 3.45:1
Faster: 3.91:1
Fastest: 4.10:1
BMW E46 - 323i, 325i, 328i, 330i

Better Fuel Economy: 3.07:1
Faster: 3.46:1
Fastest: 3.64:1

BMW E36 M3 Standard: 3.23:1
Slightly faster: 3.62
Much faster: 3.91:1
Fastest: 4.10:1
BMW E46 M3 Standard: 3.62:1
Faster: 3.91:1
Fastest: 4.10:1
BMW E90 M3 (manual) Better Fuel Economy: 3.15:1
Standard: 3.85:1
Faster: 4.10:1
BMW E90 M3 (DCT) Standard: 3.15:1
Faster: 3.25:1
Fastest: 3.45:1