A book of photography- only images of inside a car or taken from inside a car.
Could potentially be boring but the idea of someone who travels a lot being able to upload images of what he’s seen or just car fans taking a new perspective of cars. Instead of the exterior being a focus (new wheels or headlights etc.) they can show off the inside (detailing on the steering wheel, seat covers).
Wide audience for cars, an experiment to see what the would be?