My 08 GD AT fit is experiencing a drop in mileage and power. I've noticed that my car drops speed when going up small inclines. I drive the same route almost everyday, and the Fit used to take the inclines without any problems. It also seems like the car loses power or something when on any terrain. Its a subtle feeling like it bogs down for a moment and then picks up again. I've also noticed that the lights ( interior and exterior) dim for a moment sometimes. I used to get between 37-39 MPG on a regular basis. I now get between 31-32 MPG with the same driving habits and route. I took the car into the dealership a couple of times. They haven't found anything wrong with the car. I'm getting discouraged because it seems like the mileage is consistently dropping every year.

 

mmmh... I know there as been couple of problems with coil packs... maybe your spark plugs? air filter? lights dimming might be alternator+battery...
perhaps start by slow charging your car battery!

 

if the dimming is significant check your battery like was suggested. But if the battery is fine, look into the alternator.

Also some things to check:
air filter, fuel filter

coil packs could be a culprit, there's a whole thread dedicated to it and some of those symptoms sound similar.

i'm sure some others will have better suggestions. the air filter, fuel filter
might be something you can diy instead of taking it in to the dealer.

something else, when you talk to the dealer make sure to also talk to the tech. sometimes in the process of going from tech to service rep, they will dumb it down so it's easier for those not automotive inclined to understand, similar when you go to bestbuy and get your computer serviced.

i had one rep tell me i needed 3 or 4 things on my wife's car and when i asked to speak to the tech he told me what was wrong. he said "you need _ and _" which was easy enough to understand instead of being told "you'll have to get the ___ treatment immediately".

some places are better then others, good luck in your search for resolution

edit:
coilpack link

https://www.fitfreak.net/forums/1st-...e-stutter.html

 

This is great, thank you. I'm going to bring up all of this at the dealership. It seems like it may be the coil packs and spark plugs. I wish I had the device to check the car myself. I'm not to sure I trust my local dealership. I told them the car performed well with these minor inclines for the first year and a half. Their response to that is the car is just to weak to make it up an incline easily. I've really had some crappy experiences there in the past two years.

I also forgot to mention that most of my driving occurs on the freeway.