All the roads from Phoenix all the way to Rocky Point are in good condition. A 4WD vehicle isn't necessary to make the trip. There are some roads like the one pictured here in the Cholla Bay area, and the neighborhood streets in some parts of Rocky Point aren't that great either. Still, if you go slowly, just about any vehicle will be fine.
And speaking of speeds, the speed limits in Mexico are s-l-o-w. Much like here, if you drive the speed limit, the locals will be bearing down on your back bumper. The dilemma, though, is that you aren't a local, and you don't want to be stopped for speeding in Rocky Point. Add to that the fact that there are times when you can go for pretty long stretches without seeing a speed limit sign. Use your judgment here. If you are driving in a line of cars, I'd just keep up with them, without passing. If you are out there on your own, I'd stick pretty close to the speed limit, even though it will seem very slow.
Rocky Point Tip: Speeds in Mexico are in kilometers per hour, not miles per hour. Don't panic when you see that first speed limit sign. Look at your dashboard. I'll bet your speedometer not only indicates mph, but also kph.
