They were banned in racing, so little development occured.

in other news, AT&T plans to convert its entire fleet to CNG

and the NYT has a story out on how the IC engine in hybrids will shrink over the years and be tuned for a very narro rpm range

Now, suppose we took this ultra-light engine and ran it on CNG or something and used it to recharge hybrid batteries a la Chevy Volt??

i just lov it (hate it) when they feel challenged they out law a better concept
The Cummings Diesel eng. almost won the Indy 500 once
They outlawed it

I have been amazed that the Wankel has not been more popular.
Seems like a great idea ESP for aircraft ..less parts jump in around

CUMMINS!!!! There is no G. sorry but that is one of my pet peeves....
And yes it is a shame that our society is afraid of a break from conventional gas burners.

Blame my spell check............