If you are in line early to get into the park and ride RSR first thing, that will probably be your shortest wait all day. The wide right technique does help some. Get to the entrance to Cars Land as quickly as you can after you enter DCA. Many people will run or speed walk from the park entrance to get there. CMs will try to slow the runners down, buy many people ignore them. Just stay on the very far right, next to the side walk, as the mob walks down Route 66. At the end of the street, you will have to turn to the right to get to the ride entrance, so if you're on the right side of the street, you'll get there quicker. When my family utilized the wide right technique, I refused to push and shove like many others. Others will jump onto the side walk and try to get around part of the crowd as you walk through town. The CMs should make them get back on the street, but it doesn't stop people from trying to get ahead. We were probably 100-150 people back of the front of the line when we got to the ride entrance and had less than a 5 min wait to get on the ride. The line goes pretty quickly.
To ride RSR at night (highly recommended), you should get a FP. You might want to go try to catch Toy Story after riding RSR first thing since Toy Story generates a wait (40-60 min) pretty quickly that will stay consistent most of the day in the summer. Then send someone back to get in the FP line for RSR. The FP line may be long (I ended up by the animation academy in Hollywood Land), but it moves pretty quickly as well. I got to the FP machines from where I started in about 20 min. When you get to the machines, if the return time is not as late as you want, the CMs will let you stand to the side and wait until the return time is where you want it. You can hand-pick your return time this way.
If you don't have time to wait in the FP line and wait around for the return time you want, then I would suggest using the single rider line for RSR as others have recommended when you come back after dark to ride it.