In January, 2014, I purchased a Bohm Stirling car model kit that was pre-machined, thereby making it quite expensive. It was built in Germany.
But it was a car of quality machined aluminum and brass with tires of solid rubber.
The car runs on alcohol. The flame in the wicked containter at the back warms the air in the heat exchanger. It runs with a quick flick of the two brass flywheels.
I think knowing that there are models on the market of this calibre, prompted me to purchase the D51-200 locomotive and tender.
John