Yes, Kobayashi’s form exercises are sweet. 
I’ve always been interested in train design. I think it was Mitooka Eiji (check out his work), who said how designing the interiors of train is fascinating as it involves creating an entire enclosed environment—on wheels. They have more in common with architectural interiors than automotive interiors. You have to account for personal space, comfort, bathrooms, luggage space, etc. On top of that, usually trains can afford more room than aircraft interiors.
I love looking at mechanical connections and recently I went to an airfield to look at helicopters and other rotorcrafts. Looking at them up close is adrenaline pumping.