My name isn't Paul - can I still post on here? Lol.
Paul has some great tips for you! I personally went a different route, but similar to what he said, my logo has in it what was important to me. Fancy? No. But it has what I want. I knew I needed a logo but wasn't sure the best way to come up with one. I had in mind a few things I wanted in regards to color and the business image I was wanting to convey. I ended up finding the rough design on some business cards I was designing online (YouPrint.com is where I used). What originally drew my eye was the initial with the circle around it. The font with it wasn't what I had in mind so I played around with that, changed colors, etc. until I found what I wanted.
Whichever route you take, I recommend you think long-term. You'll want brand consistency. If you want a color in your logo, will that color look good on shirts, flyers, business cards, etc? What is the business image you are trying to present? What is your target market? Try to design a logo with those things in mind. I know you're just planning to start part-time, but even if you decide after 2 years that you want to pursue something else, the time and effort you put into growing your detailing business will give you good experience in anything else you get into. So I recommend looking long-term and considering what market you're appealing to.
In my opinion, it's good to keep your logo relatively simple and easy to read also. Paul's is a great example.
