First Drive: Holden Commodore SS AFM
Review by Feann Torr - 11/March/2009
a conversation with a friend about where the automotive industry is
heading, he pointed out that the media reports a lot of doom and gloom
about the future.
That's probably an honest summation. The mood isn't exactly sunny.
as we speed toward the end of the decade, we're seeing more and
more positive changes in the automotive industry.
cars are growing in number, affordable electric cars are only a couple
of years away and even locally-made cars are starting to incorporate
just spent a week test driving Holden's SS Commodore which is one
of the first vehicles in the company's new 'EcoLine' range and the
second car in Australia to use cylinder deactivation technology. It
with AFM or active fuel management which can deactivate four of the
eight cylinders to conserve fuel.
All V8-powered Holden vehicles
that are specified with the
6-speed automatic transmission now come equipped with the AFM
system. The technology is supposed to deliver the power of a V8 with the
consumption of a V6, so let's find out how it fares:
Model: Commodore SS
Transmission: 6-speed automatic
Engine: 6.0-litre, Vee 8-cylinder, petrol
Safety: 6 airbags (driver and passenger front, side (x2) and curtain airbags (x2)) ABS, ESP, T/C
Car Supplier: GM Holden
Holden's V8 models now come with cylinder
deactivation technology, called AFM, which
reduces power slightly but improves economy
Engine: 6.0-litre V8 Petrol
longitudinally mounted 5967cc V8 engine has an aluminium
alloy cylinder head and engine block. The
includes 2-valves per cylinder (one inlet, one exhaust) actuated by gear-driven pushrods
The 6.0-litre engine features a 10.4:1 compression ratio
and can use 91 RON petroleum fuel when filling the 73 litre
Max Power: 260kW @ 5700rpm
Torque: 517Nm @ 4400rpm
Top Speed: 260km/h (approx)
0-100km/h: 6.5 seconds
6-speed manual Holden V8: 270kW, 530Nm
6-speed auto Holden V8 AFM: 260kW, 517Nm
The SS Commodore we tested with AFM
showed slightly improved fuel economy
AFM gives Holden's big V8 more potential
Tech Talk: AFM
How does Active Fuel Management work? In light load conditions like highway driving, AFM automatically closes
the intake and exhaust valves in four of the engine's eight cylinders
while ensuring the engine maintains vehicle speed. This allows it to operate as a 4-cylinder engine.
All eight cylinders are still pumping, it's just that fuel is only being injected into and combusted in half of the cylinders.
engine's fly-by-wire throttle also increases cylinder
pressure in V4 mode. Holden's whitecoats say this is so the engine can preserve the torque which
drivers expect from a V8 powertrain, and could explain why the fuel use between the two AFM modes is sometimes negligible.
In operation the system is very smooth. Simply put, if
you purchased a 6-speed automatic V8-powered Commodore or Statesman,
you wouldn't know it came with the Active Fuel Management technology.
Holden's new AFM V8 cars are part of its new
EcoLine initiative, aimed at reducing emissions
I'm sitting at the traffic lights on a Sunday arvo. An
XR8 Falcon rolls up and the driver sees the shiny new SS
Commodore I'm driving. Naturally I psyche myself up for a full throttle
the lights flash green I bury the accelerator pedal,
confident in the knowledge that this new car takes advantage
of cutting-edge fuel saving technology that will allow me to be
fast yet frugal.
Unfortunately for lead foots like myself, Holden's new AFM technology doesn't reduce fuel consumption under full throttle.
Where the AFM or active fuel management system works best is when cruising.
So I try this instead: I've just hit an on-ramp to the freeway, I accelerate to 100km/h and switch
on the cruise control. The automatic gearbox shifts into 6th gear and
then the magic happens - AFM shuts down four of the V8 engine's eight cylinders to reduce fuel consumption.
essence, the 6.0-litre V8 I was driving had transformed into
a 3.0-litre V4 as the fuel delivery system cut fuel to half
The AFM system is seamless and completely
automatic in operation. You don't have to activate it or flick a
switch; whenever the car can switch to fuel saving mode, it will.
V8 Commodore's ECU or engine control unit decides when to switch to
4-cylinder mode and it only switches during very light loads.
So the burning question is this: does AFM actually result
in real-world fuel efficiency improvements?
It does, but only marginally.
When it announced the new AFM system, Holden stated that "the technology can deliver
fuel savings of up to one litre per 100 kilometres, with potential for
even better results at constant cruising speeds".
a week of testing we recorded an overall fuel consumption figure of of
13.5L/100km which is about 1 litre per 100km better than our previous efforts, but this involved 75% highway driving with
only a few short runs through the suburbs and into town.
also employed a very conservative driving style and we only applied
full throttle a couple of times to test the standing start performance of the vehicle,
which was as to be expected despite lower power and torque - very
Still, this overall figure of 13.5L/100km figure is
better than the 14.4L/100km average we recorded when we last tested the
SS Commodore, and for a 6.0-litre high performance V8 it's not too shabby.
times the AFM system works really well, switching to 4-cylinder mode as
soon as the car's road speed reached a constant, whether that was 60km/h or
80km/h. However it seemed to be most effective at cruising speeds of
100km/h and above.
"The AFM system is seamless"
all Commodores, the new AFM-enabled models are easy to live with and
are remarkably practical vehicles with masses of interior space, comfortable seats, a
decent turning circle and a cavernous boot.
They're also very
easy to drive thanks to the power steering and the trip computer is very effective as displaying a
range of different data, especially fuel consumption related
AFM-enabled Holden SS looked like any other performance model in
the Commodore range - 18-inch alloys, pumped wheel arches, rear spoiler and all
the other sporty trimmings. Small AFM badges on the car's exterior are the only overt signs of the vehicle's technology.
shift between 8- and 4-cylinder modes is imperceptible, though you can
sometimes detect a slight roughness to the engine under acceleration in the 4-cylinder mode.
once (briefly) managed to get the fuel consumption as low
as 7.0L/100km on a flat section of CityLink not far
from Melbourne city, which was in 6th gear @ 100km/h. Other
times however, the system seemed to be rather moody.
Often it worked well and would drop to
4-cylinders without a hitch - you can tell from one of the trip
computer displays when it switches to 4-cylinder mode - but other times
it was horribly ineffective (I should point out that we tested a pre-production
version so we'll request another model to give the system another test later in the year).
numerous occasions when the engine switched to 4-cylinder
mode there would be virtually no change in fuel consumption. For
instance we were cruising at 70km/h with the instant consumption
reading 11L/100km in 8-cylinder mode, and when it dropped to 4-cylinder
mode it didn't show any change.
other curiosities included one situation where we were driving downhill
and there was practically no load on the engine yet it wouldn't engage
the low emission 4-cylinder mode. Perhaps the car's computer brain had a hangover?
It doesn't take much
impetus for the engine to slip back into 8-cylinder mode either. Mild inclines
of only a handful of degrees while cruising at 110km/h on the Hume highway initiated all 8-cylinders, for
think the system would be more effective if the software that controls
activation was fine tuned even more for local conditions and it
would also be more useful if the car didn't weigh
so much. Perhaps Holden will drop the big V8 into an HSV performance
of its new Cruze when it starts building it locally in 2010? Or perhaps
Drivers who order their V8-powered Holdens - whether SS
Commodore, Calais, Ute or Statesman - with a 6-speed manual will not benefit
from the AFM technology as it's incorporated into the 6-speed
automatic versions only.
The 6-speed automatic versions may be less powerful as a result of the technology, down from 270kW and
530Nm of torque to 260kW and 517Nm, but on the road there's not a great deal of difference.
Active Fuel Management technology is supposed to deliver the performance of a V8 with the
consumption of a V6, but in reality it's more like the comsumption of a V7. It's
not the silver bullet solution to the reducing fuel consumption of large
capacity engines, but Holden's AFM is a step in
the right direction.
and hybrid Commodores have probably
been shelved in recent times, placed in the 'too costly' bin for the
time being, but AFM technology is available now and it shows promise.
The cylinder deactivation
technology will buoy interest in Holden's V8 range and though it's not
quite as good as the system used in the Honda Accord V6 we tested in 2008, it's better than a poke in the eye with a sharp stick.
is a lot of doom and gloom surrounding the auto industry at the moment and
though the cogs of industry are slow to turn, this is a positive
initiative by Holden and will be the first of many intriguing additions to its burgeoning EcoLine range.
- V8 Engine Technology
- No Increase in Price
- Handling & Ride
- Interior Space
- Sporadic AFM Activation
the review? The Car? Your Car? Email