GM Inside News Forum banner
1 - 6 of 6 Posts

·
Registered
Joined
·
2,249 Posts
Discussion Starter · #1 ·
We Drive GM’s New 8-Speed Pickups and SUVs
blog.caranddriver.com
October 15th, 2015
By: Andrew Wendler



When news arrived earlier this year that the Chevrolet Corvette’s touted eight-speed automatic transmission would migrate to GM’s full-size trucks, the C/D office responded with a resounding, “Well, that makes sense.” Don’t get us wrong, we love trucks almost as much—more, in rare instances—as we do Corvettes, but it can be hard to make headlines in the wake of the C7 Corvette’s brouhaha. Well, now we’ve sampled the General’s eight-speed pickups and SUVs.

Although GM kept our drives to a short route of nonchallenging terrain, we did get seat time in both a 2015 Chevrolet Silverado with the Z71 package and a GMC Yukon Denali, each equipped with the 6.2-liter Ecotec3/eight-speed combo. First impressions? Low-speed drivability improves by comparison to the outgoing six-speed. Under light throttle, the shifts click off in rapid-fire succession, occurring somewhere between 2000 and 2500 rpm. Leaning harder on the accelerator elevates the shift points to around 3500 rpm, all the while remaining smooth, precise, and never busy; were we not watching the action on the tachometer, gearchanges could have gone unnoticed. Floor the pedal and the eight-speed lets the 6.2-liter V-8 spread its wings, holding each gear to about 5750 rpm, just short of the 6000 fuel cutoff.

More at the Link
 

·
Registered
Joined
·
19,331 Posts
Nice to read that GM is getting the programming for the software to shift smoothly. I know it's a different tranny, but I always hated the 6 speed in my old 2008 Malibu LTZ, to much hesitation and hard shifts in certain circumstances, and I thought I've heard that other GM 6 speeds had the same issues.

Why do the pickups only getting a 1 mpg improvement while the SUV's a much better improvement?
 

·
Registered
Joined
·
4,600 Posts
Nice to read that GM is getting the programming for the software to shift smoothly. I know it's a different tranny, but I always hated the 6 speed in my old 2008 Malibu LTZ, to much hesitation and hard shifts in certain circumstances, and I thought I've heard that other GM 6 speeds had the same issues.

Why do the pickups only getting a 1 mpg improvement while the SUV's a much better improvement?
Aerodynamics.
 

·
Registered
Joined
·
15,633 Posts
Well, hang on a sec, because it just is not quite that simple.

If you look at just rated mpgs in a vacuum - with no other consideration, then the SUVs do have a stronger improvement profile..... meaning all pts ie 5.3 /6sp , 6.2/ 6sp, and finally with regard to the 2015 6.2/ 8sp regardless of whether you are comparing '14s to '15s or '15s to '15s.


Also unlike the Pick Ups so far, the SUVs had more expansion via non E85 capable offerings ( 5.3s ) - and whatever else.


Went from 4 / 5.3 offerings to 8 / 5.3s 6sp ( at GMC ) all of which are improved, and then from 4 / 6.2 offerings to 8 with 4 of those 8 having the 8sp.

( Per fe.goov - haven't checked anything @ GMC /GM. )

Lot's of nice MPG improvements for the SUVs regardless of PT.

As mentioned aero must have something to do with it but until we get a strong GM presser , think there may be more to it with regard to all of them ie all truck and SUV differences between many '14s and '15s - and @ least some '15s to '15s

5.3 6sp, 6.2 6sp, and 6.2 8sp @ GMC with regard to 'Yukon' / 'Yukon XL' appear to be nothing but a win across the board as far as rated mpgs go - when considered in a vacuum.


Maybe.... the PUs will get more .... just a little later.


While it sure would be swell to have the 8L90 / 8Lxx across the rwd board - three to six years ago.... oops, I digress.... the next group to get them into would be the 5.3 for the Pick Ups and heck, maybe even the 4.3s.

Then catch up the rest of the SUV 5.3s later........ although Cadillac cars needs an 8Lxx most of all.
 

·
Registered
Joined
·
2,408 Posts
Sounds much improved drive.....I would be pissed if I bought with 6speed.....but you got to enjoy it 6 months early.....

I think 6speed will see some depreciation from this early change over to 8speed....
 
1 - 6 of 6 Posts
Top