It's a collectible but the remaining ones can likely be improved very much with modern eBike parts, lighter and more powerful motor and batteries...
However, 3 wheelers quickly reach their limitations in turns, since you can't lean to balance. So making a C5 go much faster than its original top speed could be risky.
However, 3 wheelers quickly reach their limitations in turns, since you can't lean to balance. So making a C5 go much faster than its original top speed could be risky.