Smart cars are deceptively safe, even though they don't look it. Daimler Chrysler did a test where they crashed a big Mercedes into the front of a Smart car and the Smart car was less damaged and basicly the dummies weren't harmed. The Smart doesn't have alot of crumple space, but it does have a fairly rigid rollcage and lots of airbags. The only problem for a Smart car is the wind whips them around at highway speed, but they all have stability control to cut down on that.
Another good one for crash tests is the Mini from BMW. They did a crash test between a Ford F-150 vs. the Mini Cooper and the dummy occupants of the F-150 recieved worse injury ratings than the Mini occupants.
I'd like to see more cars like that in the US- especially the diesel engine version. The Smart car with the diesel engine gets 60 mpg (sequential manual transmission), and the Mini Cooper with the TDI gets 54 mpg (CVT or manual).