I saw this article in Slate today:
The author proposes that BMW drivers are more likely to crowd cyclists on the road than drivers of other car types. Not scientific at all, but it reflects my own perception. But perhaps that is just my own bias, as BMW's stand out more than many other car makes.
I'll add that the amount of space a driver's car takes up correlates positively with the driver's intolerance for sharing road space. Drivers of pick-up trucks and SUVs are much more likely than drivers of sedans to try to squeeze past me when its not safe. Minivan drivers fit somewhere in the middle, unless the vehicle is full of kids, in which case behavior deteriorates. Sports car drivers, being inherently aggressive drivers, are also pretty bad offenders.
The worst are the small truck professional drivers. Box trucks and landscaping trucks with trailers are often the worst. I attribute this to personal driver skill and behavior and minimal training coupled with industrial size vehicles.
Surprisingly, the most courteous drivers that pass me are the 18 wheeler drivers. They almost universally pass only when safe and with more than adequate passing space. Maybe that's because they recognize my Surly brand bike as being of the "Long Haul Trucker" model and they recognize a kindred spirit. Maybe its because they, alone in the automobile world, accept that with great power comes great responsibility.
Though I've put in tens of thousands of miles in several states developing these perceptions, this is certainly not a scientific study. You have to pay me if you want statistically valid results.