Whether a bicycle will do 40 depends on who's riding it. The new Honda Met is fuel injected and it got slower. I doubt a stock Ruckus will do much over 36 actual speed. When you put a 150cc GY6 Chinese engine in one, it completely changes the look, and costs a fortune. Many people have $10,000 into their Ruckus. Think about what kind of bike you could buy with that. A new Bonneville T100, A BMW single, a new Honda CB1100? But if it's what they want, it's their money.
I had a 2007 Met, bought brand new. After almost getting killed on it several times in town due to it's being to slow, I decided to ride it out of town on rural roads. I put 10,000 miles on it like that. I bought a Vino 125 for in town use, and also used it for long distance riding. I have 25,000 miles on it in 4 years. I just recently bought a 2012 Zuma 125, because the dealer wanted my trade in (an '09 Ninja 500) which I could no longer ride due to the painful riding position, and gave me a whopper of a trade in on it. I'm already outfitting it for long distance riding.
I looked at the C3. Loved the styling, but I was about 50 pounds over it's 170 pound weight limit. The Met had a 273 pound weight limit.
2002 Vulcan 750 (now being slowly reassembled) 2013 Royal Enfield B5
2001 XT225, 2009 Genuine Stella
1980 Puch moped