In the introduction of Anton Vanko in Iron Man 2, he stands ready to strike the helpless Tony Stark, who is saved by the timely arrival of Pepper Pots and Happy in a Bentley. They crush Vanko against a nearby wall twice, but he emerges unscathed. How? He is wearing no armor. He is not super-powered in any way revealed in the film. Why isn't he a cripple after this scene?
The scene is poorly depicted and the movie does little to explain how the Whiplash harness/exoskeletal system works, or for that matter shows the exoskeleton EXISTS below the belt line. But given that Vanko isn't in traction at the end of the scene some counteracting force must have been in play. Even if it isn't clearly depicted, Vanko must be wearing more than just a shiny chestplate.
- Vanko IS wearing an exoskeleton which enhances his strength but the region below the belt is covered by his very baggy and unflattering pants. Products released by Marvel-approved firms show the exoskeleton depicted through the pants. Perhaps such scenes were were filmed but didn't make the final cut of the movie.
From Comicbookmovie.com we get this Marvel-sanctioned graphic:
Note the enhancements on the arms. It is likely the same such enhancements are on his thighs, and calves acting as part of a strength-enhancing exoskeleton.
Given the low-speed impacts of the Bentley Happy is using as a weapon, the car was used to pin Vanko down but lacked the velocity to crush him appropriately.
If we accept that Iron Man's armor provides him with protection via strength enhancement, we are forced to consider that Vanko's provides similar support. It is likely this exoskeletal frame later becomes part of the armor he uses to battle Iron Man and War Machine later.
I'm going to link the scene in question for reference instead of trying to source pictures for everything.
There are a couple things that are questionable about this scene, and from the footage, the answers they insinuate are improbable, but they do kind of all work out together.
First, to directly answer your question, it doesn't look like he's actually wearing no armor. He's certainly not as protected as Tony is in his suit, but he is wearing some sort of brace that, at the very least, covers most of his upper body. It doesn't afford a lot of protection, but it's reasonable to assume that it'll prevent him from being totally crushed in low-impact events. While it doesn't look like it extends all the way down his legs, it's a little hard to tell since his pants are pretty baggy, and depending on how heavy the entire system is, having some support on his legs could be very useful.
Second, the speed with which they crash into him can't actually be that much. Granted, it looks like they really ram into him with a lot of force, at least on the initial crash. However, front air bags need to deploy at any crash with an impact speed above 16 mph (~26 kph) [Q5 in that link]. The airbags don't deploy until the very last time that they crash into him, so it seems like Happy was hitting the brakes before the actual collision, presumably attempting to protect himself and Pepper from a high-speed crash. Backing this up is the fact that there's very little front-end damage to the car as well. (This brings into question how the airbags deployed on the last impact, but I think it's in the realm of possibility that the sensors detect multiple crashes and deploy them then as a precautionary measure.)
Expanding on ptfreak's answer, I agree that he is supposed to be wearing armor under his pants, along the same lines as the cage-style braces on his arms.
But it's also worth noting that the "wall" he's being pushed into is really just a metal traffic barrier:
In fact, it looks like his hips might line up exactly with the lower ridge of the top guardrail. Check out the picture below: if his hips are protected, they are in a perfect position to absorb the shock of the impact and translate it back into the barrier.
Given the idea that he's wearing steel braces on his hips and legs, it's not hard to imagine that the traffic barrier might give way before his braces do. And given how slow the car was going when it hit him, it didn't even seem to do that.