Age 45, with 3600 miles so far this year.
Typical solo ride of 20-70 miles is usually around 18 +/- .5 mpg.
This is the door to door average that my computer tells me, which is the only one that counts for an average.
I just did my first century (the Great Peanut Tour in Southern Virginia) and averaged 18.8 riding with 2 other guys. Drafting helps a lot!

You didn't ask for top speed, but mine is typically in the mid 30s. I can hit 40 if I really push it. When I read about riders who casually talk about going 45-50 I conclude that they must either have really big hills where they live, or are perhaps, er, prone to exaggerate a bit...