Can a 200 MPG Carb exist? Yes. Can a 200 MPG DROP-IN Carb exist(meaning can be install on any car)? No, for the reasons Fat Charlie mentioned. If you build the engine and car around the carb(which would be hard enough as it is) it can be done, but there is no way you can build a carb that can be installed on any engine to magically make it get 200 MPG, you'd be hard pressed to make a carb that could be installed on any engine period.
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