reckons that the "oil companies" have suppressed the 100mpg carburettor
Don't ask him about catalytic convertors.
It wasn't the oil companies, it was actually the French.
In the early '90s I was designing some test equipment for use by Ford at their Dunton research base, they had a lean burn engine that produced 95bhp at 80-90 miles/gallon and bugger all emissions (GM was working on something similar too I understand). The thing was, the exhaust gas pressures were too low to blow through a catalytic converter. The French car companies didn't have such technology and they knew it was a game changer, so they cynically lobbied to EU law makers to ensure that the new emissions legislation that was being drafted detailed that all vehicals
must have cats, rather than straightforward emissions limits, allowing car makers to chose how they achieved them. That killed the Ford project on the spot.