Are you looking for a "no" answer so you can feel good about yourself so that you can say "haha, 20' isn't that tight! I win!". OK: No, I have not went out with a ruler and measured 20'.
But what I have done, is parked the car in spaced where there is less than 2' of clearance from either side of the bumper. Considering the car is 16+', and I can add 2+16+2 to get 20', I can take a pretty good guess as to what constitutes a 20' space.
You need to look at perspective, I'm guessing it's pretty easy to park in your neck of the woods around PA. It's OK to park here in VA, most spaces are perpendicular, not parallel. It's harder to park in DC, mostly parallel parking; and during events/around tourist traps, you're lucky to get a spot; and it's a lot harder to park in NY (where I take the car to constantly).
So while 20' seems like a lot of space in the boonies, it's not that big of a parking space in the city. It's all about perspective.
So don't try to tell me that a 20' space is "big" and I should go out and measure it.