2004 Neon SXT that gets about 15-17 mpgs on the High way. I am very confused about this car. We got it as a "Gas Saver" from a dealership preowned. It has 77000 miles on it and we maintain it so it doesn't fall apart. Keep the oil changed and tires inflaited and occasionally adding engine cleaner in attempts to increase the mpgs.

I looked at buying a cold air intake hoping this might increase the mileage but all the reviews are for 1 or 2 mpgs.

What should I do we do.

This is my wifes car and she is not speed demon either. If the truth be told it gets worse gas mileage when we are trying to conserve gas.

 

How are the plugs? Plug wires? Coil pack? What kind and weight of oil are you running (the weight is more important, just curious if it is a good brand )? Any noises while driving? --> Wheel bearings not performing as good as they could. What speed and RPM is it driven on the highway? Anything being carried around in the car?

What do you mean by "engine cleaner?" Fuel injector cleaner?

 

The wires look like they are covered in Electrical Tap. When I questioned that at the dealership they assured me it was fine. The wheel bearings and stuff are all fine (I think). we are using 10w30 Synthetic I believe Castrol or what ever was the most inexpensive. The drive belt squeaks... Well I think it is the drive belt

 

RPMs roll at 3500 on the High way Between 65-75n depending on what road we are on. (We travel through the mountains sometimes and to keep a good 75 miles an-hour through the hills in NE PA is impossible with out burning half a tank of gas)

 

The STP stuff that is suppose to get gide of grim on the inside of the car and make for more power/ better milage

 

If it is pulling 3500 rpm at 65-75 mph something is terribly wrong or you don't have the thing in high gear. Wife's Neon with auto pulls just under 3000 rpm between 75-80 mph. Manuals I would guess will have about the same final drive gearing. Better figure out why the thing is over-revving at highway speed. Something doesn't add up here.

 

Pictures of the wires? I guess it wouldn't make a difference if they were covered in tape, providing the wires themselves are OK. You happen to know how to test them? You may also want to take a peek under the hood with the car running at night, completely dark, to make sure they are not grounding out anywhere (in case the tape is there for a reason/"fix").

The speed sounds fine, and I'm assuming the RPM's are fine (I have an auto with no tach) as long as you are in the overdrive gear. I'm guessing you are calculating a combined average MPG by dividing miles into gallons of gas, like most do. How much highway driving would you say you do on a tank of gas? City? Mountain? I live in the mountains and I get a combined of about 20MPG or so, which is why I ask.

If you are just using that STP fuel injector cleaner, eh, save your money. If you want to do something like that, I run the Prestone Complete Fuel System cleaner or the Chevron Techron one every now and then. I believe they recommend about 3,000 miles in between the cleanings, but they clean more than just the injectors. A really good, but pricey, cleaner is BG 44K. Around $20 for a can, but it is pretty well known and used even at "high-end" dealerships like BMW. I am not sure on the interval of the BG, but I'd say you could use others after and use it for a good cleaning initially.

Here's a little bit about the Chevron cleaner: