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Old 05-25-2019, 01:28 AM   #15 (permalink)
Master EcoModder
Join Date: May 2019
Location: California
Posts: 362

Tahoe 2020 - '08 Chevy Tahoe H
90 day: 20.75 mpg (US)
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Originally Posted by Enviro View Post
So I am starting to commute about 60 miles per day which 50-55 of those miles are freeway. I am looking to get some feedback on the aero mods I am planning and which I should do first and help calculating the potential end result. I would like to get to 35mpg at 55mph which is more possible than you may think as this comes with the engine that can switch to v4 mode deactivating the other 4 cylinders.

100% stock I get about 25 mpg on the freeway but it gets in the 30's in v4 mode and I average 18.6 mpg combined city/hwy.

Mods I have already done
  1. I removed the roof rack which moved my freeway mpg to about 26 mpg hwy at 55 mph. So +1 mpg.
I also noticed that the car was in v4 mode more often than before.

Here are the removal mods I have planned
  1. Lower air dam is 78” long and 4” tall making it 2.17 SQ FT
  2. The side mirrors are each about 1 SQ FT so together they are 2 SQ FT
  3. Roof rack is 6' x 2" which is about 1 SQ FT. (Done)

Altogether this will be about 5 SQ FT of reduced frontal area.

Other Mods

Now removing the front air dam is obviously going to expose the turbulent underside of the car and expose the tires so I have a 4" lowering kit in mind effectively putting it at the same height as before.

I also have a coroplast flat bottom planned and I will replace the side mirrors with rearview cameras and 3d print the housing designed like an airfoil.

Am I missing anything and what do you think the outcome will be?

and you can get off the shelf parts:

Tahoe Hybrid Aero.. mod might be in order...

tahoe hybrid front end bumper
tahoe hybrid hood (light weight)
tahoe hybrid tailgate (light weight)(converts the rear end to Square mod)
tahoe hybrid tail lights (converts the rear end to Square mod)
tahoe hybrid D-pliller (converts the rear end to Square mod)
tahoe hybrid bumper (converts the rear end to Square mod)
tahoe hybrid rims (light weigh aero rims)
HIGHWAY Differential MOD with 3.08 gear ratio. in the rear

this will reduce the drag from 0.367 to 0.34..

the air dam reduces drag from under the suv..

on my tahoe hybrid it was cheaper buy it then try and mod something else

you can find a used one for about 10k with 90k miles..

Super Hypermiling it I'm seeing upwards 40MPG in the city and 28MPG on the highway at 59MPH I don't recommend 55MPH if you have the 6 speed you will want to do at lest 59MPH for the best gear.. ALSO you can do the HIGHWAY differential MOD with 3.08 gear ratio.

I go slowly to 30mph in EV mode (after 30mph the engine is forced on)and go straight to 41MPH =41MPG 4 banger mode.. (speed limit is 40)

If I tail gate a 18wheeler with a Trailer Tail I see upwards..
of 65MPG.. @ 70 MPH (that is how fast they are going) it stays in 4 Banger Mode

ALSO BTW I keeping a distance of about 20-25 feet (being too close does not improve the mpg nor do the 18wheelers without the trailer tail) it's not worth getting killed being 2-3 feet from the 18Wheeler trailer WITHOUT trailer tail
just to get 3-4mpg more.

with the trailer tail you can be a comfortable 20-30 feet away and get great MPG benefits with but with a EXIT plan

the square mod is the important one it's what they used on the 2015+ model to help with the mpg slightly..

those mods will be pretty expensive unless you can find a hybrid at a junk yard...

I suggest just getting the Hybrid Bumper with it's XL air dam... that will be your cheapest upgrade.. you will lose your fog lamps and hooks . just a FYI when you drop it the air dam will be 2 to 2-1/2 inches off the ground..

Last edited by Tahoe_Hybrid; 05-25-2019 at 04:10 AM..
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