📋 Speedometer Accuracy Comparison
🎯 Reference actual speed: 100 km/h
| Brand | Speedometer Reading (km/h) | Notes / Remarks |
|---|---|---|
| BMW | 104 km/h | Usually applies a constant +4 km/h difference |
| Audi | 105-107 km/h | Typical for VAG group; may vary by equipment |
| Ford (AB) | 104-106 km/h | Adjusted for European market |
| Honda | 104–106 km/h | Closer to European regulations, lower deviation than older models |
| Hyundai | 104-106 km/h | Optimized for European market |
| Kia | 104-106 km/h | Same structure as Hyundai |
| Mazda | 104-106 km/h | Moderate display |
| Mercedes | 104–106 km/h | Slightly above, usually 4–5% range |
| Opel | 104-106 km/h | Similar to GM-era system |
| Peugeot | 103-105 km/h | PSA group works very close to norms |
| Citroën | 103-105 km/h | Same infrastructure as Peugeot, low difference |
| Porsche | 101-103 km/h | Very close to actual, sporty accuracy |
| Ferrari | 101-103 km/h | Usually ±2 km/h difference in sports cars, high precision |
| Renault | 103-105 km/h | Adjusted to European regulations |
| Subaru | 105-106 km/h | Deviation also occurs in AWD vehicles |
| Tesla | 100-101 km/h | Minimum deviation thanks to GPS + sensor fusion |
| TOGG | 101-103 km/h | Very close to actual |
| Toyota | 105–107 km/h | Higher in older generations, reduced in new platforms |
| Volkswagen | 104-105 km/h | At this level in models like Golf, Passat |
| Volvo | 102-104 km/h | Low deviation, safety-focused display |
| BYD | 101-103 km/h | Compliant with ECE R39, generally low deviation |
| MG4 | 101-103 km/h | European versions close to actual, low deviation |
| Fiat | 104-106 km/h | Moderate, complies with European norms, similar to PSA group |
📌 Factory Settings
- Standard equipment, correct tire pressure, factory default values.
- Actual speed based on 100 km/h.
- This table reflects typical readings.
🔧 Additional Deviation Sources
- Wheel diameter change (16" → 18")
- Tire pressure, tread depth, wear
- Tire brand / winter & summer tire differences
- Low pressure can cause +1–3 km/h deviation
📏 Legal Framework (ECE R39)
- Speedometer must not under-read.
- Max tolerance: 10% + 4 km/h (e.g., at 100 km/h up to 114 km/h allowed)
- GPS tests typically show +2 to +8 km/h difference
⚠️ Low tire pressure leads to higher speedometer reading.
🔄 Wheel/tire related extra deviation: 1–3 km/h
📡 Typical GPS difference: +2 … +8 km/h
🧾 These values are typical with standard equipment, correct tire pressure and factory settings.
⚙️ Wheel diameter, tire pressure, tread depth, brand, seasonal tire differences can add 1-3 km/h deviation.