If you drive, you've likely felt that split-second panic: "Did a speed camera just flash me?" You were pushing the limit a bit, suspecting a patrol nabbed you—but it might just be nerves.
Besides, which speed display do you trust: your car's dashboard or the GPS app like Waze? Neither is perfectly accurate. As a driving safety expert with years analyzing vehicle tech and regulations, I'll break it down with facts.
86% of French drivers use GPS in their cars—nearly 9 in 10 juggle two speedometers. Team dashboard or Team Waze?
Purists rely on the car's speedometer (or tachograph). Here's the truth: it never shows your exact speed—by design. It reads 1-10% higher than reality, varying by model.
Example: A displayed 100 km/h could mean you're actually doing 91-99 km/h.
Why? It's a legal safeguard. Manufacturers must ensure speedometers never underestimate true speed (per ECE R39 regulation). Follow it, and you're always safely under the limit—no fines, no lost points.
Precision fans prefer GPS for real-time data. But satellite-based systems aren't flawless: signal capture causes display lag and errors.
Accuracy hinges on satellite count, surroundings, and algorithms. For the most precise GPS speed:
Neither meter is foolproof. Cross-check with roadside speed cameras (urban areas, schools). Even authorities apply margins: "measured speed, corrected speed"—subtract 5 km/h below 100 km/h, or 5% above.
The smartest approach? Drive mindfully. It'll save time for podcasts like Dying Less Stupid.
Now you're equipped with the facts.
