I live in El Paso. I've had a 2011 Chevy HHR, paint color Black Granite Metallic, since February 2012. Normally it is parked in the street. I wash it at the brushless self-serve near my house, generally at night. The bays are well lit, so I can still see what I'm doing. I use a two bucket method, washing with products I bring, not with what comes out of their nozzle. I typically do a full wash and wax about every 2 months with quick (not really, 45 minutes) rinse and dry passes in between when needed.

• Soap: NXT Car Wash. Even though this is discontinued, I deliberately sought it out because of the water softeners in it (water here is ridiculously, unfilterably hard)
• Wax: NXT Tech Wax 2.0 liquid
• Towels, etc: all my towels, mitts, are high quality. The microfiber towels are a 75%/25% polyester/polyamide blend. I have a chenille mitt and 100% cotton terrycloth towels

I wash, dry, and wax by hand, religiously following the same pattern of straight motions. The entire process takes 3 to 5 hours, 8 hours when I clayed it. When the car is clean, I'm very satisfied with the results.

Even when it's not windy, the air here is full of dirt. Not dust (animal dander, fabric fibers,etc), dirt... as in very fine particles of dried out soil.

The only time my car is actually clean is when I'm washing it. The dirt settles on stealthily, constantly. The car can look clean, but my duster will still pick up lots of it. Supposedly clean plus rain equals a leopardskin pattern of brown. After a windstorm, mine is the only car on my street that is visibly brown. Which is disheartening considering I'm the only person on my street that puts this amount of effort in.

I suspect the problem is the wax, which seems to break down in the sun and heat here. With fresh wax, after a rain I'm left with milky water runs down the sides of the car. Also, tiny flecks of wax develop all over the place (seemingly out of nowhere), which are highly visible on black paint. Water beading seems to deteriorate after about 3 weeks.

I've put off the big spring cleaning until I can get some advice here. Given my regimen and environmental factors (heat, sun, airborne dirt, hard water), what products should I switch to in order to make my car repel dirt instead of being a magnet for it?

Finally, I'm looking for interior cleaning products that are not silicone-based.