Finding a fuel efficient bike

How do you research the fuel efficiency of a bike? I'm looking for something 400-750cc and hoping to get close to 60MPG. I've been to a few showrooms and, of course, this specification is not readily available. So I take down the model and year and stuff, and Google something like "kawasaki vulcan 800 mpg" and get a lot of hits on some very subjective and contradictory information about its fuel efficiency. Is there a better way to go about this? http://totalmotorcycle.com/MotorcycleFuelEconomyGuide/index.htm has a lot of information on it, but it is not complete and again, I don't believe everything I read. The fact that a UK gallon is 20% more than a US gallon doesn't help either!
I'm hoping to get close to 60MPG. The way I drive is 85% highway, and usually don't go above 85km/hr (53mph).
If no one can help me w/that, then maybe someone can tell me which of the following are likely to be the most fuel efficient. I found them at a dealership:
Honda CB550 '83
Honda Nighthawk CB650SC '82
Honda Shadow Twin500 '83
Honda Magna V45 '82
Yamaha VStar650 '03
Suzuki Intruder VS800 '96
Suzuki Savage LS650 '04
I'm going to Google for these bikes myself, but anything anyone could add would be appreciated.

Welcome to the forum Angus.

This is a first for me. Fuel efficiency is not something that usually comes into the equation for most people when it comes to bikes. However having said that the way fuel prices are going world wide I can understand the question.

Obviously as with most vehicles your 500/550cc's will obviously use less fuel than your 800cc's or vtwins. But even then it will come down to gearing & what restrictions (depending on what part of the world you are in) are on it.

If most of your riding is highway at 85kmh there's really no need for the higher cc's so I would say go with the smaller. You'll find that fuel consumption between bikes of the same cc's will not be much different.

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*** 07 CRF250X ***