On the pad
we compared the Silverado and Tundra by executing three maneuvers to
produce front and rear wheel skidding: a sudden brake stop from 30
miles per hour with minor steering input, a sudden brake stop from
30 miles per hour with a single lane change, and a sudden brake stop
from 30 miles per hour with a double lane change.
We only
tested in 4x2 mode because the Tundra, unlike the Silverado, disables
its ESC in 4x4 mode, leaving the driver with only ABS and Active Traction
Control (A-TRAC) functions. A-TRAC is different than VSC. A-TRAC works
like a virtual limited slip differential (LSD), by applying brake pressure
to a slipping wheel to reduce speed differences between left and right
drive wheels, causing engine torque to be transmitted to the wheel
opposite the slipping wheel to gain traction. This is different from
VSC, which, again, works by measuring slip rate against some pre-programmed
threshold and can brake multiple wheels simultaneously to regain control
and traction.
In each
maneuver both trucks clearly benefited from ESC. In fact I can’t
imagine wanting to drive a pickup now without traction control because
of the enhanced safety it adds. However, the Chevy’s StabiliTrak
simply performed better than the Toyota’s VSC. There was much less
modulation noise from the Silverado’s ABS system and steering feedback
and vehicle behavior was much smoother and predictable throughout the
traction control event.
The Tundra’s
ESC intervention, in contrast, was coarser. Its brakes
were louder and it tended to let the rear slide further before correcting
the skid. Also, when the Tundra gave up its grip on the tiles, a warning
buzzer went off in the cabin to let you know you’d lost traction.
No, really? It’s an unnecessary and distracting feature that
draws driver attention away from recovery to focus on where the noise
is coming from.
That’s
not to say GM’s
setup is without fault. I spent some time autocrossing a GMC Sierra
4x4 and during one hard turn I apparently tripped a rollover sensor
which triggered an automated call from an OnStar operator to see if
I was ok. GM says they’re working to dial back the sensitivity
of the truck’s sensors to such maneuvers. It
should also be mentioned that Toyota offers VSC standard on all 4x4 Tundras,
regardless of cab type, whereas GM only offers StabiliTrak as standard
equipment on 4x4 Crew Cab models and as an option for Extended and
Regular Cabs.
But after
running through skid pad cycles twice in each truck, the simplest way
to describe the advantage of GM’s ESC over Toyota’s is
that it works with the driver rather than just for the driver.
In closing,
I’ll
echo Sam
Abuelsamid’s comments at the end of his story
about this GM sponsored event, because I think he’s in sync with
where I’m at. GM’s on a roll with its big pickups. At this
moment in time, I think they’re the best all-around light and heavy
duty trucks you can buy for the money.
But the
good news for fans of other trucks is that this will definitely push
those brands to make better rigs. There’s no other choice. In these ultra-competitive times
no manufacturer can afford not to make continuous improvements to their
current trucks and to their next generation products. All trucks are
only going to get better from here.
