I have noticed three different sounds when driving around:
1. Staticy popping noise = materials found in a crashed meteorite once shot typically render materials similar to what the planet is. I have spent several hours on Bhothos 2 or whatever the planetary moon is called, it is 34.x percent metal so I figured I would enjoy my time there hunting down things. Typically I see Iron, Zinc, Vanadium, Chromium, Sulphur, Manganese and other things pop out (common elements) after I give it 5 shots.
2. Whoohoo sound, sounds like a bad electric guitar out of tune if you are farther, but get a bit closer and it is a faint woohooing type sound, THAT means a crash or building set, but really I think it means cargo canisters. I noticed when I came across a crashed ship I heard the Woohoo get higher pitched and shorter which means you are closing in and I noticed it in several directions- sure enough, canisters that had rolled away from the site were causing that.
3. Whahah sound, sounds like the Whoohoo but slightly more metallic and it means Metallic meteorite or outcropping, which when shot a metallic meteorite gives molbdenim or whatever and some other RARE elements. Useful for making secondary type of upgraded ammo for the SRV.
My only complaint is it would sure be nice to hold 5-10 cargo canisters (affecting speed too?) so you can go back to your ship only a couple of times. Maybe even having a vehicle hanger that holds 2 vehicles you can buy an SRV and a trailer that will hold 10-20 cargo canisters. It can hover or be a ring and pintle or whatever. Heck, a hover SRV would be cool too now that I think of it, would sure make things smoother at times. On top of that, why not add special weapons or weapons period, like you find a 2A mining laser on a turret or something on a ship here and there, maybe a level 3 beam laseron a turret or straight mount or who knows, whatever. My point it it would be cool to find things you can mount on your ship, and maybe even alien tech that you can find, research and mount to your ship as well. Like in Freelancer...
Finally, I think finding only 6 canisters or so per crash is kinda boring. What if a type-9 crashed with a full load of narcotics (smuggler ship) and there was cargo scattered all over the place, like 50-200+ canisters all over the place. Or they could be generators or something else, whatever you fancy.