See the Paul Pantone Geet Reformer.
Then take away all the fringe science and here's a;
How To DIY an onboard Steam Reformer:
https://sci-hub.usualwant.com/10.1021/ef4011274
Basically; Pyrolyse the liquid fuel and mix with steam, then hope for some steam reformation using Zinc and Copper filings as a catalyst, or just be happy with the short chain gaseous hydrocarbons you get from the Pyrolysis.
MIT's plasma reformer shrinks the system down by adding more temperature and an unbeatable catalyst surface area, otherwise known as a plasma arc.
Now you start getting to the point where you are improving the power to weight ratio of the vehicle and thus true economy (urban driving) and some shell company will buy you out and shelve the tech.
But no reason why one cant build what is essentially a giant spark plug yourself.