W-platform (2003)

Pontiac Grand Prix (2003)

Being the first car built on the W-platform, Pontiac Grand Prix is also the first one to receive a second phase makeover to extend its aging life for another 3 years. The modifications covers many areas, but mostly concentrate on improving chassis rigidity, NVH filtering, a new exterior styling and interior packaging.

Grand Prix is the most sport-oriented W-car. If you order the hottest Comp G version, you will get not only stiffer suspensions, bigger wheels and tires but also a 260hp version of the Series III 3.8-litre supercharged V6 to enable a 6.5 seconds 0-60mph acceleration. Compare with the previous generation Series II, the Series III has drive-by-wire throttle to allow the installation of StabiliTrak stability control which alter throttle to correct under / oversteer. Naturally aspirated version has its output remains unchanged at 200hp and 225lbft, while the supercharged version gains 20 horsepower thanks to a more efficient Eaton supercharger. However, from its reluctance behaviour at high rev you are always reminded that it is still a pushrod engine. The not-so-beautiful supercharger noise doesn’t help subjective feeling too. A big Nissan V6 revs much cleaner and sounds more melodic.

The improved chassis feels really rigid and, at 1625kg, it is not overweight for a car so big. Even though for use in Pontiac, even in the Comp G version, the setting of suspensions still bias towards the soft side, offering smooth and quiet ride. The drawback is a handling not sharp enough to excite keen drivers. Similarly, the Magnasteer II electric power steering is well weighted but feels artificial. Admittedly, a storming front-wheel-drive platform incorporating a compulsory 4-speed automatic and riding on all struts suspensions is, shall we say, just a pseudo sports saloon. It is not supposed to be a real one. Highway overtaking is fine, thanks to its torquey V6, but don’t expect much fun in twisty roads.

Inside, the cabin is packaged with better quality plastics and assembled more solidly. Nevertheless, competitors have also up the game and I’m afraid the GM needs to take a bigger step. The in-your-face styling of dashboard and lack of attention to details still trouble the GPX. Space, however, is not lack of. Only very tall passengers may complain about headroom at the back due to the coupe-style roofline. The improved GPX is more user friendly, with 60/40-split rear seat and a wide and easy-to-access boot. Front passenger seat can fold down to place long items, very MPV-like.
 

The above report was last updated on 5 Apr 2003. All Rights Reserved.
 

Pontiac Grand Prix GXP 5.3 V8

As GM's supercharged Series III 3.8 V6 has retired recently, the top Pontiac Grand Prix has switched to a new 5.3-litre small-block V8, just like sister car Chevrolet Impala SS. The all-alloy push-rod V8 is actually lighter than the iron-block V6. With an output of 303 hp and 323 lbft, it is also considerably more powerful and torquey than the outgoing engine (43 hp and 43 lbft up). The problem is: can the Grand Prix's front-wheel-drive W-platform handle so much grunt?

GM answered this question by adopting an unusual combination of tires: the 255/45WR18 front tires are much wider than the 225/50WR18 rear tires. This make better use of the power at front wheels and reduces understeer. On the other hand, Bridgestone specially developed the stiff sidewall tires to reduce torque steer. In addition to 10 mm lower ride height, stiffer suspension setup and Bilstein dampers, the Grand Prix GXP handles much tidier than you would imagine. There is still some torque steer under hard acceleration and mild understeer in corners, so you won't assume it a competitor to the rear-drive Chrysler 300 and Infiniti G35, but to a front-drive machine the result is already surprising.

The GXP takes about 5.7 seconds to do 0-60. That's a solid performance but you can find faster rivals. With plenty of torque from the V8 and an automatic gearbox, the emphasis is effortless performance rather than outright acceleration. Still, there are a lot of outdated designs of the W-platform left to be desired - the monster length, the 1650 kg weight, the 4-speed gearbox, the boy-racer look, the low rent interior, the artificial steering feel… now in addition to a push-rod V8, maybe Pontiac has gone back to the musclecar era?
 
The above report was last updated on 7 Oct 2005. All Rights Reserved.
 

Chevrolet Impala (2005)

Last year, Chevrolet sold 290,000 Impalas in the America, making it the third largest selling car in the category just behind Toyota Camry and Honda Accord. The selling points of the car are mainly low price and practicality. However, as the even cheaper new Hyundai Sonata entered the scene, Impala may not retain the same sales result this year, even with the revision introduced in 2005.

The revision concentrates on 3 areas: 1) facelift, 2) new engines, 3) minor tuning and stiffening. The facelift is quite pleasing. It reshaped the nose and tail to look sleeker and smarter than the dull-looking old car. And then the front end structure is stiffened, the engine mounts improved and the suspension setup retuned to reduce noise and vibration. The result is a 50 kg increase of weight. The steering is also retuned to improve response and feel, though it will never be regarded as a driver's car.

Impala now adopts the new generation 3.5 and 3.9-litre V6s from Pontiac G6. Though both engines still employ push-rods ohv, 2 valves per cylinder and a heavy cast-iron block, they have a variable cam phasing system to improve efficiency. Power output is 210 hp and 240 hp respectively, considerably higher than the old 3.4 V6's 180 hp and 3.8 V6's 200 hp yet drink less fuel. However, while power matches that of the Japanese and Korean rivals, their smoothness and eagerness still lag behind the world standard.

Surprisingly, Chevrolet Impala re-introduces the SS badge with a new small-block 5.3-litre V8, codenamed LS4. The pushrod V8 pumps out a respectable 303 horsepower and 323 lbft of torque. It also has DOD (Displacement On Demand) function, which can shut down 4 cylinders to save fuel when the engine is running at light load. Even mated with a 4-speed automatic (compulsory on all Impalas actually), the V8 can push the 1682 kg car from rest to 60 mph in 5.7 seconds. This might match the slightly more powerful and slightly heavier Chrysler 300C, but don't forget the Chevy Impala SS is a front-drive car with all MacPherson-strut suspensions. That means horrible torque steer. The addition of V8 is more an advertising tactic than a call from keen drivers, who had all bought a Chrysler 300C, Dodge Magnum or Dodge Charger.

However, to comfort-seeking buyers, the Impala is quite satisfying. The Impala is always a big car with longer than average wheelbase. That is an inherent advantage to ride quality. Now with additional NVH suppression works, the cabin becomes remarkably quiet and the ride is pretty refined. The cabin also received a lift in materials and trim quality, plus more comfortable seats. In this way, most of the weaknesses of the original Impala has been sorted out.

The Impala is by no means outstanding, but it is not a bad car either. For those who care price and practicality more than image and driving pleasure, it is still a reasonable choice.
 
The above report was last updated on 4 Sep 2005. All Rights Reserved.
 

Chevrolet Impala SS

While you think the 268hp Camry or the 265hp new Altima the most powerful family sedans you can buy in the America, GM is putting a 303-horsepower, 323 lbft 5.3-litre V8 into the engine bay of Chevrolet Impala SS. Yes, it is the same “small block” push-rod V8 as last year’s Pontiac Grand Prix GXP. It wants to use astonishing grunt and tire-smoking acceleration to lure Americans back to the domestic brand. The Empire strikes back !

Patriots, don’t get excited so early. Although there is nothing wrong with the engine (apart from a little thirsty), the chassis fails to cope with the extra power and torque. The outdated W platform is not a good basis for a performance car. How can its front wheels, suspended by MacPherson struts, withstand the torque from a V8 engine ? especially when there is neither limited slip differential nor equal-length half shafts to relieve the torque steer ! and how to deal with wheelspin ? a traction control applies brake to the spinning front wheel, so the engine power shift discreetly from one wheel to another, ruining the steering.

You might remember Pontiac Grand Prix GXP employs wider tires up front than the rear to reduce understeer and a set of specially developed Bridgestone with stiffer sidewall to reduce torque steer. They work quite well in the Pontiac. Unfortunately, Chevrolet Impala SS gets none of these. Not just that, it even increased the final drive ratio from 2.93:1 to 3.29:1 in the attempt to improve acceleration further. This amplifies the torque steer and wheelspin problem. I think its project manager must be either ignorant or mad.

Another problem is the lack of suspension upgrade. The soft tuning leads to plenty of body roll and pitch to ruin any confidence. By the standard of fast-going family sedans its handling is already poor enough, let alone rear-drive rivals like Chrysler 300C. Other aspects are no better, ranging from the boring 4-speed automatic gearbox (still no manual mode) to the dull steering. The Impala SS must be developed at a very tight budget.

The only merit is the V8 engine. You can enjoy its lovely rumble-bumble and streams of torque on highway. If you can find a straight long enough, you can experience very strong acceleration too. But this talent is too limited. The bottom line is: GM has put a good engine into a wrong car.
 
The above report was last updated on 12 May 2006. All Rights Reserved.
   

Buick LaCrosse (2004)

When General Motors is replacing both Buick Century and Regal with a single model called "LaCrosse", even after the death of Oldsmobile Intrigue (together with the century-old brand), you know a lost of market share is estimated. The demand of American-style full-size sedans has been shrinking for years, mainly eaten by the Japanese (Lexus and Infiniti in particular) and Sport Utility Vehicles. However, there are still many old customers buying such cars every year. What they want are very simple - a lot of cabin space, a comfortable ride, an affordable price and lastly, an American brand. That's why GM decided not to spend too much money into the development of LaCrosse.

Apparently, the easiest way to save money is to design the LaCrosse based on its predecessors. That means it also share the W-platform with Pontiac Grand Prix, Chevrolet Impala and Monte Carlo. All-strut suspensions are not anything to be proud of for such a big car, but it guarantees low production cost, which translates to a significant price advantage over Japanese saloons. Moreover, it is reasonably stiff and quiet, thanks partly to a new aluminum front subframe.

Measuring over 5 meters in length and have a 2807mm wheelbase, LaCrosse is able to sit 5 big guys in comfort. Moreover, being a front-drive machine its rear seat is not obstructed by transmission tunnel. Predictably, the cabin design is conservative to please the old people who buy it. Fake wood and so-so quality plastics might be an improvement over Century and Regal, but fall short behind its foreign competitors. Again, cost control is the driving force behind that.

LaCrosse offers a couple of V6 engines. One of them is the familiar 3.8-litre push-rod engine. Now updated to Series III, it complies with the latest emission standard and received a new intake manifold to reduce induction noise, but its uninspiring manner remains unchanged. The iron-block engine produces just 200 horsepower, translating to a low power to weight ratio rarely seen today. The only good news is that Series III will be the last evolution of the push-rod V6. GM will replace it with multi-valver eventually.

Another engine is a cheapened version of Holden / Cadillac's 3.6-litre dohc 24-valve V6. This is a world-class engine, featuring variable valve timing at all 4 camshafts. What a pity in the Buick application it is detuned to 240hp and 225lbft, while Cadillac CTS 3.6 provides 255hp and 250lbft. The peak torque is actually no more than the push-rod V6, therefore performance is just average, especially it is mated with a lazy 4-speed automatic. However, the multi-valve V6 is definitely a more lovely choice than the Series III V6, as it revs cleanly towards 6000rpm and sounds much more eager.

The "updated" chassis is not really so updated. It still employs very soft springs and dampers compare with foreign saloons. Yes, the setup is already sportier than Century and Regal, body movement is now better controlled, but you know Century and Regal were never famous of handling. Like them, LaCrosse is tuned to please customers in their 50s and 60s. Their sore backs need a supple ride to take care. Don't talk about driving fun to them.

Externally, LaCrosse looks every bit a modernized saloon. However, underneath the skin is actually very conservative and outdated. Chrysler 300 and Ford 500 will give it a hard time, so are many Japanese saloons. Buick had better hope it has enough loyal customers.
 

The above report was last updated on 15 Oct 2004. All Rights Reserved.

Specifications

Model
Pontiac Grand Prix GXP
Chevrolet Impala LTZ
Chevrolet Impala SS
Layout
Front-engined, Fwd
Front-engined, Fwd
Front-engined, Fwd
L / W / H / WB (mm)
5037 / 1875 / 1417 / 2807
5090 / 1852 / 1490 / 2807
5090 / 1852 / 1490 / 2807
Engine
V8, ohv, 2v/cyl.
V6, ohv, 2v/cyl.
V8, ohv, 2v/cyl.
Capacity
5327 cc
3880 cc
5327 cc
Power
303 hp
233 hp
303 hp
Torque
323 lbft
240 lbft
323 lbft
Transmission
4A
4A
4A
Suspension (F/R)
All: strut
All: strut
All: strut
Tyres (F/R)
255/45WR18 / 225/50WR18
All: 225/55R17
All: 235/50R18
Weight
1650 kg
1655 kg
1683 kg
Top speed
143 mph (limited)
114 mph (limited)
154 mph*
0-60 mph
5.7 sec*
7.4 sec*
5.6 sec*
0-100 mph
14.8 sec*
20.1 sec*
13.9 sec*
 
Figures tested by: * C&D
 
Model
Buick LaCrosse CX
Buick LaCrosse CXS
-
Layout
Front-engined, Fwd
Front-engined, Fwd
-
L / W / H / WB (mm)
5032 / 1854 / 1458 / 2807
5032 / 1854 / 1458 / 2807
-
Engine
V6, ohv, 2v/cyl.
V6, dohc, 4v/cyl, VVT.
-
Capacity
3785 cc
3556 cc
-
Power
200 hp
240 hp
-
Torque
225 lbft
225 lbft
-
Transmission
4A
4A
-
Suspension (F/R)
All: strut
All: strut
-
Tyres (F/R)
All: 225/60 R16
All: 225/55 R17
-
Weight
1585 kg
1618 kg
-
Top speed
N/A
N/A
-
0-60 mph
N/A
7.0 sec*
-
0-100 mph
N/A
19.4 sec*
-
 
Figures tested by: * C&D
  

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