It seems that you can argue that a CAI will increase gas mileage (more air flow) , but you can also make a pretty good argument as to why your mileage would go down (more air/fuel mixture).

Has anybody out there lived with the stock intake for a while and tracked the mileage before and after installing a CAI, like the TRD or AEM?

 

your mileage won't go up. the reason you get a cai is for more power, the reason why it makes more power is because your sucking in colder, denser air so you can add more fuel. therefore, your will use more gas and your mpg will go down as a result.

but it isn't a big increase in power, and it isn't a big decrease in mpg. but it is there.

 

Good points above, I'd also add driving habits will change with the CAI. At first especially you'll want to hear it and feel it to justify it in your own mind so in driving harder there goes your MPG.

 

That makes sense. I actually had a CAI in my previous truck but I installed it when I first got it and drove it for 5 years. I think when I drove lightly enough to NOT hear the CAI, then my mileage went up. I suppose the difference is due to driving style and not because of the presence of a CAI system.

 

I disagree.

Think about it like this; two cars going the same route driven by identical drivers (think Attack of the Clones but with xBs instead of Wookies). One has a CAI, one has the stock intake. Because of where the stock xB intake is, the CAI really does not get air any colder than the stocker...the benefit in HP is from the reduction in restriction.

To accelerate at the same rate on the same road, each car will need its engine to generate the same amount of power. Because of the lesser restriction, the CAI car's driver will not need to open the throttle as much. What this means is that the throttle essentially puts the restriction back in the intake tract that the CAI took out. In the end, they will get basically the same mileage...if driven the same. The better sound and additional power may encourage fast driving and fuel consumption, but the intake alone won't do it. The main benefit of a CAI on the xB is to reduce restriction.

 

CAI's from what I have heard and experienced generally give a small to moderate boost in power for a small loss of fuel efficiency. This is exactly what I have experienced with higher flow replacement air filters as well, altho the the gains are less than a well designed intake.

I have run a K+N Tsunami CAI for about 11k miles. The mileage is slightly less (I think less than 1MPG) the way I drive it with a noticable increase in throttle response when I need it. I can certainly tell a difference in power when accelerating briskly. I drive moderately most of the time, accelerate smoothly and quickly but not briskly. My car is a 2006.5 xB but the results should be similar on any car. I average 27 MPG, most of my driving is stop and stop rush hour traffic.

 

My manual-shift xb2 has close to 8000 miles now. With TRD cai, these are my ACTUAL mileage comparisons:
Before install, best tankful was 30.6 mpg, worst was 27.55.
After install, best is 29.41, worst 26.96.

TRD cai sound is very throaty, but evident only with an enthusiastic foot. And, I can FEEL THE POWER.

Avg mpg instrument display is not close to accurate. It shows numbers between 1-4 too optiimistic.

 

Not to highjack, but what about a less-restrictive exhaust's effect on fuel economy?

 

zip, zero, zilch, nadda, none.

intakes effect mpg because they increase the volume of air going into the engine, which means the engine adds more fuel.

exhaust has nothing to do with that, it just leads the gas out of the engine, the more efficient, the better.