Differential Ratio Guide
The differential ratio significantly affects acceleration, top speed, and fuel economy.
Available Ratios (E46 Platform)
Section titled “Available Ratios (E46 Platform)”| Ratio | Source Model | Character |
|---|---|---|
| 2.93:1 | E46 325i auto | Taller, more relaxed cruising |
| 3.07:1 | E46 330i manual | Balanced, OEM for manual 330 |
| 3.15:1 | E46 ZHP | Slightly shorter |
| 3.23:1 | Various | Performance upgrade |
| 3.38:1 | Various | More acceleration-focused |
| 3.46:1 | E46 330i auto | OEM for auto 330 |
| 3.62:1 | E46 M3 | Shortest, most aggressive |
Effect on Driving
Section titled “Effect on Driving”- Shorter (higher number): Quicker acceleration, higher RPM at cruise
- Taller (lower number): Slower acceleration, lower RPM at cruise, better fuel economy
Ratio Swap Considerations
Section titled “Ratio Swap Considerations”- Match speedometer calibration when changing ratios (coding change needed)
- Shorter ratios pair well with manual transmission for spirited driving
- Ensure the differential type (168 vs 188 vs 210) matches your subframe