Having ridden a vintage Moulton Speed I can say that there are few, of any standard sized bikes I have ever ridden that can roll out so smoothly and so quickly... and it has 18 inch wheels.
It is a brilliant design and this bike has been further modified by my friend.
My folder is built more for comfort than speed and it still cruises along very nicely in the 30 kmh range... I have stunned more than a few people who were riding full sized bikes.