What a great list, thanks for the link!
Thought i might add this
Old Cars Weekly - 1959 Opel Record Miles Per Gallon
Dare i add common sense to the list of suppressed tech
i mean jeez look at the list of record holders.
"The previous record of 49.73 m.p.g. was broken in 1939 by a 1947 Studebaker achieving mileage of 147 m.p.g.; in 1969, a Fiat 600 established a record of 244.35. In 1973, McMullen’s 1959 Opel P-1 Hardtop shattered that record with its 376.59 m.p.g. result"