The scenario I've heard, and this may be the urban legend talking, is a quick disabling swipe at the achilles. At which point speed becomes less of an issue.

The car would have to be sitting fairly high off the ground for a normal sized guy to fit underneath it. My Honda is VERY low to the ground. I've changed the oil on it and there is no WAY a human is crawling underneath there unless it's on blocks.

Of course there are the leprechauns to worry about.

Also, the guy hiding underneath the car is in serious danger of getting run over if he misses his swiping and doesn't then get out of the way of the tires in time. The more you think about it, the less likely the scenario sounds, doesn't it?

It was tough watching those puppies, but somebody had to do it.

Long ago I read a book set in my era (i.e. roughly 1800-1820) where a husband didn't believe his wife was a virgin on her wedding night because she didn't bleed, but was eventually convinced by a Learned Medical Type that sometimes it happens that way and he really ought to believe her protestations of innocence.

God knows I read enough novels with this as a device. I think it is often (although I'm not sure accurately) described as resulting from a lot of horse riding.

Attention, certaines images peuvent choquer les personnes sensibles au froid!

Ganked from tnh's Particles at Making Light:

Freezing Spray On Lake Constance

Images from the lakefront on a very windy, very cold day -- icicles in unbelievable shapes and angles, docks covered in frozen waves of ice.

Now those cave formations in Kartchner seem a little more explainable....

Those are beautiful pictures, Theodosia. I'm certainly choquée.

(although I'm not sure accurately)

I'm pretty sure it's plausible -- NSM with the a lot of horseriding, but more that a lot of horseriding gives many opportunities for it to happen.

Steel cut oats! With honey, a banana, and a shot of cream. Nummy.

Yeah, when I look at the room under my car ... it seems a lot of work for not that much payoff. There have to be easier ways to mug a woman.

Okay -- now that I've found the gel I wanted for the plants -- now I can't remember the name of the plant -- a simple vine, non-flowering IIRC, white and pale green leaves, and pretty much grows just fine in water -- anyone know what I mean?

When one is looking to make sure there's not a guy hiding under their car -- what sort of attack is the guy going to launch?

The urban myth, at least, is that he's going to slash your ankles with a razor and then leap out. Although, upon thought, there's no leaping from under a car, unless you're talking about an evil leprechuan.

Or he could just grab your ankles and yank them towards him, which would dump your ass on the ground right quick. Granted, he would still have to army-crawl out from under the car to continue the attack, by which point odds are decent that the victim would have stood back up, but psychologically it's a good tool to get the victim offguard.

Snopes addresses the guy hiding under the car story. [link]

Or he could just grab your ankles and yank them towards him, which would dump your ass on the ground right quick

I don't think that would be easy. I'd think he'll need to yank your ankles quite a distance to make you fall (maybe a foot?) which means he has to grab you while you're still a foot away from the car, yet stationary. If he's that close to the edge of the car, isn't he visible? And he'll need to yank them both to make you fall.

Oddest thing I saw on my way to work today: half a rabbit, on the lawn of a univeristy building.