So I feel that I see way more hand car washes than automatic ones these days - I think the last time I was in one I was a kid. But in the US, the opposite seems to be true. This article does a great job at looking at the changes in trends in the market. There are some nice diagrams to draw based on it - I'll probably do this with Year 13 so they can practice shifting AR/MR/AC/MC curves, but it could work for Year 12 too.
If you don't already subscribe, Jadrian Wooton's Monday Morning Economist newsletter is worth a look for interesting, teen-friendly articles.