If your vehicle has any significant mileage on it, there's one super easy thing you can do to improve gas mileage.
Clean your MAF sensor. How do you do it? There's a lot of YouTube videos. All auto places have the cleaner. You can do it to any modern vehicle that uses metal sensor pieces in the unit. (older ribbon style ones like from 80's and 90's are different) It's beyond easy. Typically a screw driver is the only tool needed. You pull it out, spray it clean many times (bottles say 10), wait 10 minutes for it to evaporate, then put it back in. Never touch any of the pieces and don't use anything but MAF cleaner. Make sure you spray the metal bits you see inside, not just the plastic.
You'll make back the $10 for the cleaner within the week if you drive much. Maybe even one day. It depends a little on if you reset the computer by disconnecting the battery. The computer in cars learn over time how to adjust themselves slowly for optimal operation. You need to drive in town and on high for 45 minutes each at a minimum after a battery reset. Without doing the battery it'll just correct itself over some days.
How much mileage? That opinion varies. The stuff that gets on them is very light, to the point it's hard/impossible to see, but they're very sensitive. If your car has over 30k it's worth a shot. Over 60k you definitely should. Symptoms of it being particularly dirty can be slightly more difficult starts and declining fuel mileage. For those that wonder if it works... my fuel mileage, starting, and general running of engine greatly improves after cleaning. YMMV, but in general I wouldn't trust those that say otherwise to using it, unless you're talking very old string based units.
