OK wife just bought a 99 Bravada with California emissions .
It's epa is horrible. Wife really likes it but she's freaked over the 14.3
Mpg . I told her when we bought it that it got about 15 . However it does have a misfire so I'm going to give it a tune up and I've already changed all but rear axle out to Amsoil.
14.373 is what she's given me driving it super nice.
What can I do to help her out. Exhaust suggestions, air filters, delete the California emissions or all of them. What do you think.

P.S. thanks for the help and my old 98 past emission with punched out cat so no worries there but I'm not surest ever even did anybody on my 98. It had a Gibson exhaust to. It all helped for like two weeks I thought then the eve adjusted and right back to normal. That also had
30x '9.5x15 big Mud Terrains

 

I've had 2 jimmy's and 2 astro vans and that's about all i could get ..sometimes less , very seldom more.

 

new o2 sensors, every other tank full use a bottle of injector cleaner for 3-4 fillups. Keep the rpms under 2000 as much as possible.
2000 zr2 and i get 18 highway 15-16 city

 

I owned a fleet for a Courier & Delivery I owned for 20 years. First thing I did every vehicle I bought was replace tires with one size larger.

Improves mpg's roughly by about 1/6th; typically my delivery vans went from 16 to 18-19mpg's.

This will also throw off odometer, speedometer, will also reduce apparent power, and increase brake wear, all by about the same factor...

 

All depends on where you are driving it, and how you are driving it. It's a heavy vehicle for stop/go. Is the A/C on. Are the calipers dragging? Is the TCC operating as it is supposed to? Remember it's a heavy vehicle for stop/go if it is a 4WD.

If you have a SES light from a misfire (or even a pending misfire code without SES light), the TCC will not engage and that will cost you a couple of mpg when driving above 46 mph. I am speaking from experience here - been there done that.

I generally get 14.5 mpg in 50:50 combined city:country with the A/C on. 15.5 with the A/C off. This is operating at a max of 50 mph on country 2-lane roads, so the TCC is seldom on - but I drive to keep it on as much as possible. This means going above 46mph to get it to lock up. Will stay engaged below 46mph down to about 42 if you are not trying to accelerate. If it does get disengaged need to go 46 or above to engage again.

If I move the vehicle out to a level 4-lane highway, turn the A/C off, go 55-60 mph, and let everyone pass me - will get 21/22 mpg. Turn the A/C on subtract 2mpg, speed up to 70-75 and subtract another 3mpg (wind resistance of a box on wheels). If you TCC doesn't work for any reason that will cost you an additional 2mpg.

Best strategy is to teach your wife to drive for mileage. All the CAI and special mufflers will do very little for you in comparison.

You area at a slight disadvantage with a Bravada, as I understand it the front axle does not unlock and it is AWD. A little gas mileage is the price you pay for those soccer Moms not having to push that Auto 4wd button when they need it. I think the term they are using on SUV's for "Auto 4WD" these days is "Intuitive 4WD" instead of AWD. Unfortunately, as far as I know you can't turn it off and to me that is really stupid.

 

OK guys Bravado was totaled Christmas day. In researching for my Blazer though I found this post and I wanted to update my final mpg.

First thanks for all the help the misfire code was stopping TCC.

After a forced tuneup with Autozone Duralast gold Cap and Rotor we solved our misfire and I got Driver side tuneup completed. This got us a 15 mpg out of the Bravado and I also checked my RPO code to find we had 3.73 LSD . Transfercase was not locking in either as clutches where shot.
As of this day the engine was running Mobil 1 5w30 high mileage oil, Trans was converted to Amsoil Fuel Efficient Signature Series, Tcase was Amsoil Universal ATF Signature Series (Auto Trak II APPROVED ), front axle to Amsoil 75w90 Severe gear.

Two weeks later I finally completed tuneup , at this time I also pumped out the PS fluid till it changed pretty bright ATF red . Fluid used was Amsoil Fuel Efficient ATF Signature series. After this the Bravado cli.bed to 19.5 MPG till about December 1at or so when temps dropped.We then went down to 18.5 and by Christmas day she dropped to a 18 MPG . The PS seemed to be a key service as the completed tuneup had no engine change that could be felt.