Caveat: I swapped out my tires when I bought my bike, and I've never done a true calibration for the circumference setting in the computer. So it's possible my speedometer is slightly off.
With my Stromer, I can go above 52 km/h. Not downhill, in the plain and without wind. Gear settings are 52 / 11, this means 1rpm = approx. 10m. With a ST1, I couldn't exceed 48 km/h - even with 4 Bar, fully charged battery an all the strength I have. The reason might be the efficiency of the ST1 motor. Above 45 km/h, most electrical power is transformed into heat.
So, maybe you've met a classic Stromer. Easy to identify by the color of its motor.
Well that bike didn't have the weight or motor which these do. I would like to go faster , I wish I knew what was done. I doubt their are any of the Euro spec hot rods here in the States but maybe