Let’s continue the vintage BMW idea. Old cars obviously require quite a lot of maintenance. Many people will buy a “fixer upper” with the intention of spending their spare time repairing and restoring it. There’s a very obvious market here: a guide to restoring different BMW models. Depending on your knowledge, you could produce detailed guides for the three or four most popular models and sell them. Not everyone restoring a car will buy them, but some probably will.
A perfect example of the Active Problem Solving + Automation concept is in my online courses I’ve created over the years, or my free webinars I’ve created more recently Each of my online courses and webinars are targeted to help people with specific problems, whether that’s in the area of affiliate marketing, podcasting, building a brand, and so forth. I am always improving upon the courses, but they are also evergreen for my audience.
In June, he put ads on his site with Google Adsense, and within the first hour, earned $1.08 with three clicks. He earned $5 the first day, $7 the second, and then eventually began pulling in $15-$30 a day. In October, he created an ebook exam study guide priced at $19.99. By month’s end, he earned $7,906.55 — more than he had ever previously earned in a month. 

If you have specialized knowledge in a certain topic, you can put together an online course to teach others. For example, if you have experience in real estate investing, you can create an online course “Real Estate Investing 101”. The benefit of an online course is that once you create the course material, you can sell it to as many people as you want.