A 125cc motorcycle has variable top speeds depending mainly on the size of the bike and size of the user. Under optimal conditions, one could expect a 125cc motorcycle to attain a maximum speed of approximately 70 miles per hour.
Scooters above 49cc are classified as motorcycles. You would need a motorcycle endorsement/license.
a 125cc motorbike
Engine size you probably want a 125cc minimum. It's not too powerful and you can ride them at any age as long as you have a license.
A 125cc scooter has a sports exhaust and that makes it louder than your average ride. If you want one that is not so noisy, you will also have to go with one that is not so fast.
You have to be 16 to ride a scotter. But to ride a 125cc you have to 17
20mph
That depends on what country you're trying to ride in.
No as soon as you turn 17 you can ride a 125cc as long as it is still restricted. I did this myself when I turned 17.
56
Yes, provided you have a licence for a 125cc, or provisional licence and are displaying L plates.
real fast
Researching a number of 125cc motorcycles has shown that they are indeed considered to be fuel efficient. These bikes are commonly used in India due to their fuel efficiency.