For years, I've been trying to discern some kind of trend regarding the vehicles that I encounter on the road and the way that they treat me as a cyclist. I had a theory about red pickup trucks for a while, initiated by an episode with one that involved his horn, my middle finger, him pulling over to the side of the road, and then him driving away when I pulled over behind him. (I look small on a bike, but when I get off you can tell that I'm 6' 2" and 180 pounds ... okay, 190.)
But then I had a man and a woman in a red pickup truck pull up to me on Wilson Pike last summer, while I was riding along in the rain, and offer me a ride. I cheerfully declined -- while I don't exactly like biking in the rain, I'm not one to get picked up less than five miles from home -- but they successfully ended my prejudice against red pickup trucks.
Hummers often pass too close, but what choice do they have? They're very wide ... as are their drivers. Ha-ha, just kidding (no, I'm not). But, seriously, Hummers aren't really more obnoxious than other cars ... at least, from a cycling perspective. Besides, the price of gas being what it is lately, it costs $10 just to drive the darn thing down to the mailbox and back. With that level of conspicuous consumption, I expect them to vanish soon.
From my experience, however, the cost of the vehicle does not seem to have any correlation with how well or poorly the driver treats a cyclist. I've been passed too closely by BMW roadsters and Mercedes Benz sedans, but I've also had them move into the other lane and hang behind me for a mile on a curvy road. On the opposite end of the spectrum, I've been buzzed by rusted out Gremlins and coddled by the last surviving Ford Pinto.
As someone who frequently rides both downtown and way out in the country, I can also tell you that there is no big difference between rural and urban drivers. On quiet back roads, rural drivers typically have more room to pass safely, so they do. On busy city streets, urban drivers may end up stuck behind me moving a little more slowly than they care to, but they usually just wait until a good spot to get around me. You could, maybe, make the argument that city drivers are less likely to run you over because there are more witnesses, but I think most of them just realize that getting past me doesn't really gain them anything since we will both be waiting together at that next red light.
I would not expect any difference based on the race or gender of the driver, and have not seen any. If there is a difference based on age, it's that very young and very old drivers tend to be a little more extreme. Many young drivers are not used to passing cyclists, so they either go too far in the "safe" direction (sometimes crossing to the shoulder on the other side of the road) or they just pass as if you aren't there. Very old drivers often behave the same, but when they pass you closely it's because that they really may not see you due of the cyclist-shaped cataract in their right eye.
So, you may ask, is there no way for a cyclist to spot the driver to avoid?
It's a subtle thing, and you may have to get a dorkiscope (also known as a helmet- or eyeglass-mounted mirror, although one of those that goes on your handlebars will work, too) to see them early enough, but you should watch out for the ones whose time is obviously more valuable than yours is.
This is the guy that passes the school bus as the "Stop" sign is coming out, or pulls out onto a busy road when there really isn't a good opening, forcing the next three cars to tap their brakes. He will cheat down the other lane that ends in 100 yards just to move up a few spaces, because this means that he can get home 30 seconds earlier than he otherwise might. And he really needs those extra 30 seconds.
Now, maybe this person is going to use those extra 30 seconds to cure cancer or bring peace to the world, in which case I do not begrudge them their ill behavior towards other cars. But often they're just trying to get home to watch a "Two-and-a-Half Men" re-run, and there's a good chance that they might hit a kid coming out to that school bus, or cause an accident when they count on somebody's brakes being good. There's also a chance that they will pass me on my bicycle in a blind corner and find themselves facing an oncoming semi, and --- since their time is so valuable they certainly can't waste any of it in a hospital -- they come back into my lane and ... crunch!
Ultimately, the only thing that any of us really has is time. We get to choose how we spend it -- with loved ones, making money, curing cancer, watching sitcoms, being a shmuck, or riding a bicycle. Beware the person who wants to cut short your time just so they can have a little more.