2016 5.3 V8 with 8 Speed loses 1 MPG

raym0016 · October 14, 2015

Most likely due to 3.42 gearing as the only option with the 8 speed and 5.3.

http://www.fueleconomy.gov/feg/PowerSearch.do?action=noform&path=1&year1=2016&year2=2016&make=Chevrolet&model=Silverado%20C15%202WD&srchtyp=ymm

http://www.fueleconomy.gov/feg/PowerSearch.do?action=noform&path=1&year1=2016&year2=2016&make=Chevrolet&model=Silverado%20K15%204WD&srchtyp=ymm

I was thinking the opposite would happen and it would gain 1 MPG but apparently it isn't.

Rawyzf · October 14, 2015

Is it losing 1mpg vs the 5.3 6sp with 3.42?

raym0016 · October 14, 2015

Is it losing 1mpg vs the 5.3 6sp with 3.42?

Probably not but the 5.3 6 speed with 3.42 wasn't tested by the EPA, only 3.08 was. I would guess that it is even with the 5.3L 6 Speed, MPG wise.

TxTruckMan · October 14, 2015

Right. I'm betting it's because of the gears - 3.08 vs 3.42.

fondupot · October 14, 2015

Well that's weird. I would think the 5.3 would see a little bump in mpg with the addition of the 8 speed. Oh well.

Rawyzf · October 14, 2015

Apples to Apples, 5.3 with 3.42 has to have a mpg gain going from 6sp to 8sp.

BigBadSierra · October 14, 2015

Well I say they have something wrong as all of the 2wd 2016 seem to have the same millage as the 2015 4WD.

http://www.fueleconomy.gov/feg/Find.do?action=sbs&id=37012&id=34675&id=34677

Unless the new body lost a full mile per gallon on all of the 2016's

I would say the numbers are not right.

arkenzo · October 14, 2015

But doesn't the 2016 5.3 make more hp/tq?

TxTruckMan · October 14, 2015

But doesn't the 2016 5.3 make more hp/tq?

Nope. Same exact engines.

raym0016 · October 14, 2015

Well I say they have something wrong as all of the 2wd 2016 seem to have the same millage as the 2015 4WD.

http://www.fueleconomy.gov/feg/Find.do?action=sbs&id=37012&id=34675&id=34677

Unless the new body lost a full mile per gallon on all of the 2016's

I would say the numbers are not right.

The difference in that link is the 8 speed vs. the 6 speed. I would say that it is accurate. As said, the base ratio is 3.08 on the 6 speed but the 8 speed (5.3) is only offered with 3.42. the EPA can only test what they are given and I assume the manufacturers need to supply a vehicle they would actually sell, hence the 3.42 being used with the 8 speed. The question is why didn't GM pair the 3.08 with the 8 speed? Maybe they know something we don't? I think the 1MPG swing would have went the other way with 3.08 gears but at the expense of smooth acceleration/driveablilty.

TxTruckMan · October 14, 2015

I think it's because the 8 speed is only available in the upper trims, and those come standard with the 3.42 gears. I don't think you can get the 3.08 in LTZ or SLT for 2015, can you?

redwngr · October 14, 2015

2015 GMC

GU4 Rear axle, 3.08 ratio

Base Sierra - Standard and only available on (L83) 5.3L EcoTec3 V8 engine. Not available with (RD3) 20" ultra bright machined aluminum wheels or (NZM) 20" chrome aluminum wheels.

SLE, SLT - Standard and only available on (L83) 5.3L EcoTec3 V8 engine. Not available with (RD3) 20" ultra bright machined aluminum wheels, (NZM) 20" chrome aluminum wheels or 22" LPO wheels.

And since 5.3 is standard on SLT, 3.08 is standard on slt (and 'available' on the others)

OmahaBen · October 15, 2015

I don't get it. Why is a 3.08 gear even offered?

redwngr · October 15, 2015

??

raym0016 · October 15, 2015

I don't get it. Why is a 3.08 gear even offered?

To improve gas mileage on EPA tests with the 5.3L and A6. The interesting thing is that almost all of the 2015 5.3L LT's in my area had the "optional" 3.42 gears.