Yes. mileage is measured the same in all vehicles.
go to fueleconomy.gov for answers to all consumer vehicles gas mileage
Of course not. It's a function of weight, engine size, driving habits, aerodynamics, etc...
If this vehicle has high mileage I would start with the plug\wires and oxygen sensors. These would all affect fuel mileage on higher mileage vehicles. Hope this helps you.
Depends entirely up on the miles per gallon that vehicle gets. All four-cylinder vehicles do not get the same fuel mileage.
This is one of the best sites I have used and the most comprehensive in terms of information on gas mileage on vehicles, there you will find all the information you need. http://www.cars.com/go/advice/Story.jsp?section=fuel&story=mpgClass&subject=fuel List
Use the same rule as for passing motorized vehicles in almost all instances.
So far, for a given weight and volume, batteries will hold less energy than a fuel tank. All-electric vehicles gets less mileage per charge than combustion vehicles get per tank.
Some Hybrid cars have great gas mileage. They have a wide range of vehicles that range from gas mileage of 39 to 48 miles per gallon. It all depends on what kind of car that you are looking for and that should help determine the miles per gallon.
All OBD2 cables are not the same but all have the same type of connector on the end. This makes them universally compatible with all ODB2 vehicles.
Consumer Reports publishes an annual comparison of all vehicles and their rankings. They give all sorts of information to make comparisons, and give their picks for the best pickups and other vehicles.
No it does not give you better gas mileage, all it does is helps with any loss of horse power and white smoke coming from the tailpipe due to burning antifreeze.