I use the dollar store equivalent of these products with great results.

WD40 - This is great for making your engine area Super clean. Just spray around engine making sure you don't spray open electrical parts and wipe down with a rag.

Mean green - this stuff will make cleaning your alloy wheels a snap. Totally wipes out brake dust and grease.

SOS Soap pads - I was suggested this by a local muffler shop. I uses these on the chrome muffler tips and was truly surprised. This will not scratch the surface and totally eliminated all the rust while bringing back that chrome shine.

I'm sure you all have other tips on detailing. These are just a few.