Since the craze is hype, so are the demand of autonomous vehicle, as per Roland Berger and Forschungsgessellschaft Kraftfahrwesen Aachen, the 5 major countries considered to be the top pioneer in AV segments are:-
USA,
Germany,
Sweeden,
The UK and
South Korea.

The market in 2017 shows that European countries are highly competitive and are marking their position in the leading segment in the AV segment. Somehow, China and Japan didn’t score in the top 5, but scored the position, after South Korea consequently.
However, as per a report by IW Köln, the maximum patent holder for autonomous vehicles are from countries such as Germany, the USA, Japan, and France.
Source:- Statista