Mild Dirt Duty Exposes Weak Approach Angle - 2015 Chevrolet Colorado Long-Term Road Test

Edmunds.com

Mild Dirt Duty Exposes Weak Approach Angle - 2015 Chevrolet Colorado Long-Term Road Test

I brought our 2015 Chevrolet Colorado Z71 4x4 to the Gorman Ridge rally as a support vehicle and was reminded of its terrible approach angle.

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legacygt

I frequently comment here about my frustrations with Ford for putting undersized turbo engines in their larger vehicles (Explorer, F150) in order to inflate their CAFE and window sticker MPG numbers. So it would be unfair for me not to call out GM for using these aero tricks to improve their fuel efficiency. I'm all for making cars and trucks more efficient. But a truck is a truck and an SUV is an SUV. GM seriously impacts the capability of Colorados and Sierras and Tahoes (and the GMC equivalents) by affixing these air dams that reduce ground clearance to sedan-like levels. How ridiculous is it that they are selling people running boards to climb into tall trucks and SUVs that could barely clear a curb? Of course, these things can be removed (or broken off) and GM's approach is still more honest than Ford's because you can actually come close to achieving the MPG numbers they report but it's still worth calling out.

jfa1177

Its all done in the name of aero efficiency. They are there to clean up and get the air below aerodynamically dirty under carriage bits. Manufacturers are in a tricky place with the popularity of CUV/SUV/Trucks and the need to meet CAFE requirements. I'm not giving anyone a free pass but this is a simple and cheap way to better aerodynamics. Mind you the new Taco uses an air dam but it doesn't interfere with the approach angle.
On the flip side, most people will never see anything close to a trail with these trucks or really any truck for that matter. Most are suburban posers who have an image to maintain. Those who do use the truck for off-road use will remove the air dam. In my area which is nothing but cattle land and cotton fields almost every truck is missing the lower bumper. They've either been torn off crossing a rutted field or traversing muddy single tracks to the deer camp. These guys/girls don't give much though to fuel economy.

simpled99

I think the best thing is to remove it and see how much it really affects the MPG. If I owed it, i would remove it.

brenro

Just get a Tacoma.

nate001

simpled99 said:

I think the best thing is to remove it and see how much it really affects the MPG. If I owed it, i would remove it.

I was going to say the same thing. But it may be hard to replicate the conditions (Wind Speed, Traffic, Air Temp) to get an accurate test. If the difference is negligible (+- 1-2 MPG) then keep fascia off.

The driver should also not know if the fascia is on or off when they are running the tests so that does not influence driving style, would need to blindfold the driver until they are in the truck.

hoseclamp

Or come up with some new fasteners that make it a 2 min job for your people to undo this lip spoiler, instead of the hour its going to take to get all of those factory fasteners off.

ebeaudoin

nate001 said:

I was going to say the same thing. But it may be hard to replicate the conditions (Wind Speed, Traffic, Air Temp) to get an accurate test. If the difference is negligible (+- 1-2 MPG) then keep fascia off.

The driver should also not know if the fascia is on or off when they are running the tests so that does not influence driving style, would need to blindfold the driver until they are in the truck.

Agreed. They could use the fuel economy loop they've used in the past. There are always variables but if they kept the driver, route and timing the same they could get a good idea.

tlangness

jfa1177 said:

On the flip side, most people will never see anything close to a trail with these trucks or really any truck for that matter. Most are suburban posers who have an image to maintain. Those who do use the truck for off-road use will remove the air dam. In my area which is nothing but cattle land and cotton fields almost every truck is missing the lower bumper. They've either been torn off crossing a rutted field or traversing muddy single tracks to the deer camp. These guys/girls don't give much though to fuel economy.

And this is the Z71 Off-Road version of the truck, yet the owner's manual still says this:

"Caution: Operating the vehicle for extended periods without the front fascia lower air dam installed can cause improper air flow to the engine. Reattach the front fascia air dam after off-road driving."

(From Dan's update about the RTI here: http://www.edmunds.com/chevrolet/colorado/2015/long-term-road-test/2015-chevrolet-colorado-ramp-travel-index-take-1.html)

metalmania

Supposedly it's good for around 2 mpg (highway I assume). I think that's what GM said, but I don't recall where I read it. It's really no surprise that it didn't do so well, with the previous approach angle test and by visual inspection it's obviously pretty low. Given that this truck is the Z71 package that's supposedly optimized for off-road use, it really should at least have some kind of quick release mechanism. I know I've seen an off-road review of the Colorado somewhere that said it did pretty well, but I remember looking closely at the photos and noticed that they had removed the air dam. Don't some Jeeps have a quick release setup where you can remove the whole lower front fascia for off-roading? Seems like something similar for just the air dam shouldn't be a big deal to do.

milt721

"Caution: Operating the vehicle for extended periods without the front fascia lower air dam installed can cause improper air flow to the engine. Reattach the front fascia air dam after off-road driving."

Interesting. No warnings about crawling at very low speeds about air flow - even when the air really isn't flowing at all, but driving at posted speed limits without the air dam causes improper air flow.

bgsntth

I just procured a 2016 Suburban with the Z71 package. Happy to report it does not have the aero-facia/air dam;, but a short plastic skid plate continuing to a thick metal skid plate. Why the Colorado Z71 has the street-oriented set-up is perplexing.

allthingshonda

milt721 said:

"Caution: Operating the vehicle for extended periods without the front fascia lower air dam installed can cause improper air flow to the engine. Reattach the front fascia air dam after off-road driving."

Interesting. No warnings about crawling at very low speeds about air flow - even when the air really isn't flowing at all, but driving at posted speed limits without the air dam causes improper air flow.

Probably because the Colorado uses electric cooling fans. At low speeds and idle there is no natural air flow so the fans will operate at high speed if necessary but at highway speeds the fans turn off because highway air flow is more than what the fans can produce anyway. They will only come back on at highway speed if coolant temperature gets too high. GM, for decades, has used air dams under the bumper to direct air flow to the radiator and condenser. Instead of like the Japanese and Europeans, who have no air dams but usually have cut outs in the lower bumper to expose the radiator and condenser to the air.