Speed Limit Problem: Troubleshooting & Solutions

I have a question regarding the maximum speed (Vmax) guaranteed by the manufacturer (is it actually guaranteed?). My 66 kW SEAT Leon struggles to reach 175 to 180 km/h on the speedometer. Occasionally, the needle even reaches 190 km/h (4000 RPM = 181 km/h), which would be the stated top speed. However, this value is rarely achieved. In addition, I had a powerbox from Datatrans Electronics installed by the dealership (it was part of a complete package). For the first few thousand kilometers, I didn't think much of it. But after 13,000 km, the Vmax should be consistently and easily reached, especially since the powerbox should increase it further (Vmax + x).

Jetzt habe ich erst mal meinen Frust beim Autohaus abgelassen. Die wollen das Fahrzeug mal checken. Da bin ich aber äußerst skeptisch, daß die da was auf die Reihe bekommen. Vielleicht ist ja die Powerbox defekt. Kann es dann sein, daß zu wenig Diesel eingespritzt wird? Ich habe festgestellt, daß er selbst bei Vollgas oder hohen Drehzahlen kein bisschen rußt. Mir ist allerdings aufgefallen, daß er nach ein paar Sekunden Standgas anfängt zu pfeifen. Das Geräusch kommt aus dem Auspuff. Tritt man nun einmal aufs Gas, ist es für kurze Zeit verschwunden und kommt dann wieder. Die Werkstatt meint, daß wäre normal (irgendeine Schwingung überträgt sich bis zum Auspuff). Was meiAre you listening?

Since the vehicle is only 4 months old and I still have the full warranty, I certainly won't be tinkering with it myself. However, I would like to point out a few possible causes to the workshop. And what major problems could possibly arise after only 13,000 km (80 km daily commute + approximately 3,000 km on the highway)?

And once again: Is it correct that the specified maximum speed must always be reached (even in bad weather conditions), or is that not guaranteed?

Hi,

Please use the most secret functions of the forum.

CU Gremlin.

Hi,

Since all speedometers tend to show a higher speed than the actual speed, every car should theoretically be able to reach its maximum speed as indicated on the speedometer without any difficulty. For safety reasons, you could check on the highway while driving at a constant speed how much your speedometer deviates from the actual speed, or whether the combination of different tire sizes and tolerances is causing a significant discrepancy.

The 4000 RPM you mentioned seems to correspond quite well to approximately 180 km/h, so your speedometer in this range is likely to have the usual overestimation of about 0 km/h.

Without a power booster, you should easily reach that point. With a power booster, you'd need to go quite a bit further, as it's already close to its performance limit at 4000 RPM. While the performance starts to decrease there, an additional 200-400 RPM is usually achievable with typical gear ratios, provided there's enough power.

Regarding the initial running-in period... I drove my 81kW Ibiza, which had about 1600 km on the clock, briefly towards its maximum speed for the first time. According to the speedometer, it reached almost 200 km/h (the maximum speed is 193 km/h), but it wasn't "flat out" and only for a very short time. Moreover, as it turned out later, there was a leak in the charging system at that time. Today, it reaches 200 km/h on the speedometer without any difficulty, even when going slightly uphill, and usually it reaches 205 km/h, and under good conditions, even up to 210 km/h. According to GPS, 210 km/h corresponds to a real speed of 200 km/h, so 205 km/h is a real speed of 195 km/h, which is slightly above the maximum speed.

With a Box, your car should also be able to achieve that, especially since the 90 hp engine is usually geared slightly differently, meaning it can convert power into speed more effectively than the 110 hp engine.

"Why don't you run the 'Ulftest' (search function - > described many times) and post the results here? Compared to other cars with similar weight and engines, it should be possible to see if there's a lack of power."

Best regards,

Jan.