VAspeed3

A calculation based on only one tank is subject to plenty of error. You have to fill up to exactly the same level as you started the tank with to get the real number. It may sound silly, but that means you have to fill up at the same pump facing the same direction -- the level of the car, the temperature of the fuel going in, and the delivery rate when the pump stops automatically all have an effect on how much goes in before the pump does stop.

Take an average over several tanks to get close to the real number.

glennco

I completely agree on that assessment. Last weekend we had the car out on a road trip, and each tank was right around 29.5mpg. One tank was exclusively road driving, with the cruise set at 73 for nearly the entire tank. As of now I'm basically saying that this is something that I need to put up with to get the zoom zoom factor.

That also being said, if I could have found an '06 or a stick I think I would have gotten it for the extra gear(s).

My current plans for increasing the mileage are as follows:

1: Clean throttle body - The car has 33000 on it now, so I assume this needs to be done
2: Install K&N air filter - reports on this bbs seem to state that this will give me a couple mpg.

Any other thoughts?

thanks again for all the good comments all

VAspeed3

I'm not sure how much the automatic soaks up on the highway compared to the stick; probably not much at all. Seems your car should do a little better that 29.5 on all highway trips. My Speed3 does nearly that, but only if I stay under 65 or 70 MPH. You should get over 30 at that speed.

Maybe I should try it, but I seriously doubt you will get an extra 2MPG out of just an air filter. If it worked, I'm pretty sure the car would have come with it new.
Cleaning the throttle body may be needed, but don't expect it to make noticeable difference in mileage unless there is gunk affecting the MAF or something like that.

jzoomer

if you have never owned a k&n filter that statment is dead...it does help most cars even more than 2mpg....my uncle has a 04 3.5 v6 nissan altima and he drove down from VA. (6hr drive i think) but at 70 mph i think he averaged 26mpg...put a k&n filter in it before he went back and on the way back he averaged 30mpg

_Kansei_

My mom had an 03 and 05 V6 Nissan Altima and got 16mpg all the time.. a full 6 hour highway drive maybe 22 lol

but yeah, a high performance air filter will help a lot, I'd just steer away from the K&N oiled filter mess. It really messes with the airflow sensors on some cars. AEM makes a high performance dry filter 'dryflow' that works really well and isn't messy!

jzoomer

crap....maybe i was wrong about the figures i dont exactly remember the numbers...but he did get 4+mpg better on the trip home with the K&N

_Kansei_

she also has a lead foot. but even when I drove it 6 hours straight flat highway before @ 69mph I only got I think 24?

I can get 36mpg @ 75mph on that same highway trip in my wagon

glennco

The real issue with the automatic in pre -06 models is that it only has a 4 speed tranny, and the rpms are well over 3 running at 70mpg.

After many years of using k&n air filters, MAF issues are typically due to overoiling. If the k&n is lightly oiled as its supposed to be, there shouldn't be any MAF issues

VAspeed3

OK, but was that just a one tank calculation? If so. it's plenty suspect. I've had single tank calculations show I got only 25 MPG when I should have done much better, and had them show 31 MPG when I know I could not have done that well considering the conditions of driving in town a fair amount with some hard driving that I know soaks up fuel in a big hurry. The number you get on any one occasion is all about the fill-up.

glennco

Last night I installed a new K&N, and cleaned the throttle body.

It's amazing how dirty a throttle body can get after 2 yrs and 32000 miles.

needmazda

as i said before i hope to have a 3 next week, can anyone tell me where the tach sits at 80mph, one with turbo, and the one without, any info would be greatly app thankx

zzoomp09

Regular M3 2.3 5MT, tach sits around 3500 at 80mph. Not sure though but I'll take a look on Sunday. I won't be on a place anywhere in Manhattan where I can run at 80mph tomorrow.

zzoomp09

MZ3 2.3, 5MT... Confirmed: tach sits at 3500rpm's at 80mph.

VAspeed3

The Speed3 runs about 2400RPM at 60MPH in 6th gear, so 3200RPM would give you 80MPH.

KyanMarcus

ok My car just reached 500 miles, I assumed it's passed its break in period or what not, but why is my trip computer still showing I'm only getting 19.4 mpg ?? I mean I drive slow and taking it easy. Why am I getting such sh*tty mileage? I thought I'd at least get 25 or something, but 19? This is basically like owning a jeep! GRah!