Abysmal mileage

[**DONOTDELETE**]

I have a 99 maxima se suto. Since day one, the mileage has always been abysmal. I have never achieved ever the published city mileage (25mpg) during highway driving! The best I have ever achieved was 24mpg with top speed of 100kph (about 60mph) for most of the driving. Car is serviced as per schedule and all recommendations in manual are followed. I don't drive it hard either. I mentioned it at 12,000km service and they changed the air filter without my permission. http://forums.freshalloy.com/forum//images/icons/mad.gif That sure helped a lot. http://forums.freshalloy.com/forum//images/icons/rolleyes.gif

I insisted that there was something wrong with the car and they ran a diagnostic on the emissions, and replaced a faulty rear oxygen sensor. It helped bring me up from about 18mpg back to about 20-22mpg combined driving.

Is this poor mileage normal, or am I missing something? I thought the Maxima was one of the most fuel efficient six-cylinder gas engines around. The salesman told me the Max would get better mileage than the Altima. http://forums.freshalloy.com/forum//images/icons/confused.gif

Fuel costs are killing me, as my commute has increased, and at least in Canada, fuel costs have increased by 38% in 1999 alone! http://forums.freshalloy.com/forum//images/icons/shocked.gif

Anyone have any suggestions?

[Nismo]

One of the single biggest causes for poor gas mileage is an oxygen sensor that's not working 100%. The oxygen sensor in most cars is mounted on the exhaust manifold near the engine. Does the Maxima have two of them, one in front near the engine and the other nearer the muffler? If so, I'd replace the one that didn't get replaced earlier.

[**DONOTDELETE**]

With my 95 Maxima I got 21-22 mixed and 26-28 on the open road, so you are not too far off the mark.

[TitaniusMaximus]

Get your ECU checked... sounds like your car is running too lean or too rich... and it could be a bug in your ECU... especially if you already had a Oxygen sensor replaced... I would seriously take a look at another dealership if I was you... since you got taken with a horrible deal and now you are getting bad service... With a 99 Max SE (auto) you should get around 20-22 mpg in city and around 30 in highway driving... I got as much as 33 mpg during a 1200 mile trip... most of it was on the highway doing over 80 mph... haha... don't tell the cops!