[LeanBurn]

-Get a Scanguage, the details it tells you will allow you to see the results of your driving methods far better than reading about them. Driving style is 90% of the battle. Once optimized other mods contribute...

-I run Prius wheels on my Corolla. They are very light and they chose them for a reason. If you can't find Prius wheels that will fit, see if there are light alternatives as previously mentioned. Aero modifications make more difference at highway speeds. At city driving speeds momentum of course is your ally and aero mods will play a smaller role. No to the spoiler over rear window. You want to keep the air flow attached. Do an upper grill block, leave the bottom open. Look at putting a bumper chin to radiator pan with coroplast (super cheap and effective).

-Can your car shed any weight? Getting stuff all out trunk except for essentials...then more aggressive measures, seats etc.

-Run as skinny tires as advisable. Stock size is 175/60R14 skinnier would be 165/65R14 or even 155/70R14 would work and still keep fairly accurate speedo. Keep them aired up to 40psi or more to provide the lowest rolling resistance.

-Get fresh transmission fluid.

-Plug in block heater on 3hr timer for your morning commute to have everything warmed up and ready to provide optimum fuel combustion faster.