Gas mileage.
 

Bought a new 05 Civic LX Coupe four cylinder 115HP automatic tranny. Senior citizen not a hot rodder. New it got 22 - 23 MPG and I wondered why it didn't get 29 like it is is suppose to but now has almost 1000 miles on it and yesterday I filled it and got a great 29.2 MPG and I was delighted. Wondering why the sudden jump in mileage and if anyone who bought a new one ever experienced the same. No drastic change in driving habits, just around town and I'm the only one that ever drives it. Huney.

You can't accurately measure gas mileage unless you drive mostly highway miles. City driving has too many variables. Also your car won't fully break in for another 20k miles. I am at 40k miles now using fp60 and lc20 from lubecontrol and getting average 40 mpg on the highway with alot of mods.

Also, breakin has alot to do with MPG. I noticed huge jump around 12,000-15,000 on all my civics, it went from high 20's to mid 30's consistantly. Same thing happens when you get a car new. My truck had an average of 12 MPG when I first got it, after 1000 miles it was at 15 and now at 10,000 miles it's at 18-20 MPG.

Thats not good. I've got almost 4,000 miles on my 05 sedan ex 5sp. 1st tank was 37.0 mpg. 2nd tank was 38 mpg, and todays fill-up was 438 miles with 11.1 gal of fuel = 39+ mpg. I drive 22 miles a day for work total, 14 on the freeway and 8 miles stop and go plus the normal running around, kids to school, shopping etc. You should be seeing mid 30's with an auto.