Try this web site at http://www.maintainyourcar.com
If you ask on the forums you will be sure to get an answer
They should help increase the fuel economy, it all depends on what model
What car do you have?
yes it can
Full tune up will certainly improve gas mileage. plugs, wires, cap/rotor(if DIS, then doesn't have), fuel filter, air filter, pcv valve to name a few.
plugs at around 100,000 miles. blow out or replace the air filter. replace the fuel filter.
Swap out your stock ecu chip with a high performance one it can increase hp and mpg.
Basically, not really, they are what they are. Engines were not build for fuel economy and alterations to that end are essentially an exercise in futility.
Spark plugs, spark plug wires, air cleaner filter, oxygen sensor, fuel filter, and plenty of air in your tires.
25 to 40mpg
NO. It has NOTHING to do with the MPG.
There are many factors and way to increase the MPG in your Metro. Tire pressure, timing, spark plugs, air filter, fuel filter. I also found this place to be very helpful http://www.teamswift.net/viewtopic.php?t=17057
unleaded
Typically a "fuel-efficient" car will get at least an average of 30 MPG. Anything below that is not considered fuel-efficient. Anything under 20 MPG is labeled a "gas guzzler."
try hotter burning spark plugs. and you should try a higher grade of gasoline it may cost a little more per mile but it helps the engine run clean. there for your miles per gallon will improve. plus try cleaning your air filter and running some fuel system cleaner through it to to clean the carb. and what not.