BimmerFest BMW Forum banner

Improving 1996 1.9L Z3 Gas Mileage

4K views 21 replies 10 participants last post by  vintage42 
#1 ·
Any pointers?
 
#3 · (Edited)
Yes driving slower and over inflating tires has been affective, thank you. Yes, I am referring to ecu optimization, feul system flushing, cam rotations, boost-less turbo, or any other mod that has been tried an proven. I would even consider an entire engine overhaul, or since it is currently an automatic making it manual, or gutting it and replacing everything with the latest most efficient technologies.
 
#5 ·
With mods like you are talking, you will NEVER recoupe the money spent in fuel savings. If you want bragging rights, by all means go nuts but don't kid yourself thinking you will be saving money. Driving slower with a well maintained car will wield the best bang for the buck.
 
  • Like
Reactions: pauladrianghx
#9 ·
You may be correct. Cost is certainly a concern. Great thing about this car is that I can do most of the work myself. I intend to keep the car for life, so perhaps I recover the savings even though petroleum supply is projected to run out in 100 years give or take 50 years. I guess waiting for a shop that can or acquiring knowledge on how to make this car a hybrid or all electric might make sense.
 
#16 ·
Every time I drive my '98 Z3 2.8L I don't even think about gas mileage, I guess I am having to much fun to think about it. I have average a over 30 mpg, but then I am not having as much fun.

But honestly, I don't believe there is much you can do to improve mileage except to make sure it is tuned up and tires a little over inflated and take it easy on the throttle.
 
#18 ·
With an OBD II engine, none of those affect fuel economy, only maximum performance. The computer will optimize performance around those variables. Dirty air filter? Right behind it is a Mass AirFlow Sensor. Bad Plugs? The front oxygen sensor will detect that, up to the point of a complete misfire, which will set the Service Engine Light. Low fuel flow? Oxygen sensors will detect that as well.
 
#19 ·
With all respect, it's actually the other way around. OBDII is a monitoring system first and foremost, and will correct for problem areas to maximize for performance not fuel economy. If the engine is compensating for restricted air flow to ensure maximum performance, it will burn more fuel.
 
#21 · (Edited)
The job of the OBDII engine controller is to achieve optimal combustion.
I saw a demonstration once where they gradually blocked the air intake to simulate the effects of a clogged air filter on a standard OBD II-equipped sedan. Eventually, the car barely had enough power to move on its own, however an emissions probe in the tailpipe showed within-spec emissions, meaning the car was completely burning the fuel and wasting none. There was no way to get additional economy out of the engine. That's because the engine computer reduced the fuel amount to match the available air for combustion.
The effect of limiting the airflow was identical to reducing the throttle position.

Here's a video story from Rock Auto that explains it as well:


On the other hand, here is an example of the performance impact of a dirty air filter:
 
#22 · (Edited)
The 1.9 is the most economical Z3 engine already. My best tank was 31.5 mpg. Since I got the car about 15 months ago, it has gone 5,580 miles on 196.6 gallons, for an average of 28.4 mpg. Seems good to me. The only way to get better mpg is to drive with less acceleration, but using the engine is the fun of a sport car.
BTW, what is your mpg that you want to improve?
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top