As you noted, you did pick stuff up, but for crisp listening that's about it. If you run the squelch all the way down, you'll pick up a lot...including 99% static and unwanted noise.
Remember too, I used a 4 watt radio for reference. Most trucks run 10 watts and up, and some are even legal...:laugh:. What I have is available at any good CB shop (often located in truck stops) and can hit clearly on flat land at 8-10 miles. It's not ummmm...quite stock. If you want to know any more than that you need to talk to a CB shop and read up on the laws governing radio use.
I bought my 5000 since the last time I ran a CB on a car. The 1000 did just as well for me on the trunk lid of my '96 Buick Regal as the roof of my truck (for my purposes, which are similar to yours). The 1000 is definitely enough for your needs and would save you a little money. The 5000 rocks because it threads onto the mag base. I run with my base on all the time. When I want to run the radio, I screw the whip on. It's nice because the whip is so long, but also for theft issues. You can cut a good antenna off at the base and replace the cable for CHEAP! So good mag-mounts are easy game to those sorts.
I didn't think to ask...one of the most common problems for new people to radios is not understanding the squelch...did you turn it all the way down to see what you pick up? You want to adjust that now and then. Out in the sticks you can run it all the way down, but the closer to cities (congestion) you get, the more you'll want to turn it up. It's an adjustable level of what you actually hear vs. what's on that freq. If you want to hear what's within say 1/4-1/2 mile from you but don't want the fuzzy signal from 1 mile or more, you listen to somebody loud and clear while turning that knob up until the background crap fades away. If you want it all, that's what you get...ALL of it.
I should also mention, it seems CB use is down considerably in the last years. More drivers every year would rather talk on their phones and other devices. Much less traffic info than I remember years ago.