Yes it is interesting fuel consumption on carburetors, My Stanza rally car (Violet or New 510 in the US and elsewhere) was pretty much Full group two factory car with many "Works" components Engine wise Std capacity Japanese L20 B block 11.3 CR either Early 219 casting Big Port SSS head ,Usual 44 mm inlets but 36 mm exhausts Factory group 2 cam 76 Degree 48 mm Webers 40 mm Chokes 4.875 Final Drive on 195/70 14 Dunlops SP 52 R E compound and on the few occasions I actually drove it to an event instead of Tilt Tray it averaged 36 MPG around 75~80 MPH.

I also had a factory FIA Cylinder head group 2 Legal FIA spec and that made even more torque and got another 3 MPG on transport stages, However in Competitive Stages it averaged 12 MPG in Dry conditions and got down to between 5~6 MPG in wet conditions.

Tom in fact the best power from Bike Carburetors I ever saw was replacing the Japanese Carburetors on Kawasaki's with smoothbore Mk 2 Amal carburetors, those babies really make good power when you dial them in.
They are round Brass plated smooth bore type carburetors not flat slide style but they really mix the fuel well and hence make good clean smooth power, they Jet up really well.

The Big trick in getting them to work was Cam and Ignition dialed in before fine tuning the Carburetors and that applies to anything, But even some of the best in the game do not get cam timing where it should be, My car with a 76 Degree cam pulled from a good 500 RPM earlier than other examples of similar spec engines.

It was actually more fuel efficient than My Stanza Coupe , Fuel Injected L20 B ex Howard Marsden and George Fury so having been the personal car of the Nissan and ex Ford Motorsport Manager in Australia (Howard) and then taken on Hand by George the Factory Rally and Bathurst Driver for Nissan it was nicely set up, But the Rally car was more economical because it was more efficient.