Externally looking, Commodore VT is exactly the same as Omega, except minor differences in detail. In fact, it is considerably bigger in all dimensions. Here is the dimension comparison between Commodore and Omega:
 

While the chassis is new, the suspensions are modified from the previous generation Commodore VS, which was based on the previous Omega. In other words, MacPherson struts up front and semi-trailing arms located at the rear. The setting is relatively hard to cope with the ultra-rough Australian country roads. 

For engines, Holden did no favour on the refined German Ecotec V6. Instead, they adopted GM’s pushrod engines for lower cost, ease of service and production reasons. (V6s are produced locally) Base model is powered by the Series II V6 displacing 3.8 litres. With 197 hp and 224 lbft, it is high on torque but not really smooth and quiet by world standards. Next up is the supercharged version outputting 230 hp and 277 lbft, but its existence is threatened by the top of the range LS1 V8, coming from Chevrolet Corvette / Camaro / Firebird, with lower state of tune it still pumps out a massive 295 hp and 330 lbft. Just mind the fuel consumption. 

While the V6s feels inferior to foreign competitor’s multi-valve V6s, the V8 offers sports car performance at a low price, that makes the Commodore so special. Here, we are talking about 0-60 mph in six seconds or so even in the automatic form. Of course, high performance should be matched with a good chassis, otherwise it would have been just another Chevrolet Impala SS. Obviously, Commodore does much better, especially is the SS model. The chassis is strong, the steering are sharp and accurate, suspension setting bias towards a bit handling than ride, massive 235/45 VR17 tyres provides a lot of grip ... what’s more, the rear-wheel-drive chassis is happy to play power slide game !  

Less satisfactory is the transmissions. Two of the three gearboxes come from GM, including the popular 4-speed auto and six-speed manual for V8. The former works well but with neither adaptive electronics nor sequential manual mode, so no fun at all. The 6-speeder has the last two ratios too tall, thus works like over-drive. The remaining is a 5-speed manual from Getrag. Probably the best of all, what a pity its service is limited to the least powerful V6. 

Compare with European and Japanese cars, Commodore is not renowned for refinement. The suspensions do not iron out bumps as well, the pushrod engines feel harsher, the cabin trimming looks as cheap as the car actually is, poor fit and finish of plastic parts in cabin, and poor grade of plastic too. Space and comfort, however, are superb. Benefited by the extra size, it has plenty of room front and rear. Seats are big, soft yet supportive. The size of boot is no less impressive. 

The bottom line is : being the best-selling family sedan in Australia, Commodore has done very well to suit Australia's needs as well as to give European and Japanese car makers a lesson. The best family sedan it may not be, but it reminds us what is driving fun. Sometimes sacrificing refinement for driving fun is worthy, especially when the rest of the world is overcrowded with refined cars. I just hope the globalisation of car industry will never spread to Australia. 
 

HSV Commodore GTS

The same could be said for the latest GTS. HSV got all the components from the market (huge brakes, LSD) or from GM’s parts bin (LS1 V8, transmissions, ABS, traction control), put them together, plus a little bit modifications, and a TWR-designed aerodynamic kits ... here comes the GTS. The advantage reflects in the price tag - in UK, it’s just two-third of a M5; in Australia, the gap could be only larger. On the down side, there’s not a single innovation or interesting technology to be mentioned. Motor journalists might not like it .... 

Not until they drive it. Let’s make it clear: the GTS is really good to drive. Base on the Commodore SS 5.7, the GTS has a lot good elements to begin with - an all-alloy V8 closely related to Chevrolet Corvette (actually comes from Camaro and Firebird) and a rigid chassis. The American-built 5.7-litre V8 is already capable to pump out 300 hp in normal form, with a little bit modifications, including the adoption of a huge exhaust, power rises to 335 hp, or just 10 hp inferior to Corvette. Without surprise, it has a lot of torque - maximum 349 lbft. 

As experienced in Corvette C5, the power delivery of this LS1 engine is very linear, still with massive of bottom end torque but no longer as lazy to rev as older generations small block V8s. That’s not to say it could rev freely to 6,000 rpm - after the 5,600 rpm peak, power runs out quickly. This is still a push-rod engine. For the same reason, it’s not deemed to be a smooth V8 compare with competitors - provided you regard M5, E55 AMG, XJR and S6 as competitors of course. The huge exhaust generate brutal and low frequency noise that might excite someone, but some prefer the pure mechanical noise of dohc engines. 

Noise is rather subjective, but stop watch isn’t. Launch the Commodore GTS in a tyre-smoking style, it can overcome the 1.7-ton inertia and hit 60 mph in merely 5.7 seconds. That’s better than Audi S6 and not far away from Jaguar XJR, BMW M5 and Mercedes E55. At 13.8 seconds, it breaks the 100 mph barrier. M5 did that in 12.7 sec, XJR in 12.8, E55 in 13.0. The HSV follows well those expensive European machines. 

Braking is equally impressive, thanks to the huge disc brakes - 343 mm diameter up front and 315 mm at the rear. Moreover, they are cross-drilled like Porsche 911. The brake pedal is also well weighted. 

Suspension design is not the most sophisticated - front MacPherson strut and rear semi-trailing arm as in the normal Commodore. (HSV is developing a new multi-link rear for the next generation GTS) However, stiff setting and good choice of dampers result in rock-steady body control. Roll is just minimum, a thing also thanks to the low profile tyres. Predictably, ride quality is not so good. It is harder than all the aforementioned rivals, although not to the extent that feels discomfort. Steering is quick and accurate. It requires just 2.5 turns to go from lock to lock. 18-in 235/40ZR18 tyres provides a lot of grip to match with the good body control.  

GM’s 6-speed transmission is still a weak link. Not only it’s heavy to shift, but the sixth gear is actually an overdrive. That limit the top speed to 152 mph which is obtained at 5th. Otherwise, the GTS is hard to criticise. Apart from the superb performance and handling, it has all the good ingredients of the lesser Commodore, such as huge cabin and boot space and high equipment level. Moreover, HSV gifted it beautiful sports seats. If you don’t mind the cheap-looking dashboard (even though with chromed panels added) and a little bit lack of refinement, the GTS is the most attractive choice in its price range. Climbing up to the M5 etc. requires a really helpful bank manager. Shopping elsewhere at the price range will find a BMW M3, Audi S4 and Mercedes C43 ... too cramped and not all that inspiring to drive as the brand names suggested. So, before the new M3 appear, HSV Commodore GTS is the car which I’d recommended. 
 

HSV Commodore GTS 300

However, the GTS 300 is already the fastest saloon currently available, marginally beating BMW M5 and Mercedes E55 AMG. This must thanks to a Callaway-prepared LS1 V8 pumping out 300 kilowatt (which gave its name) or 402 horsepower. Again, that’s marginally more than the more expensive M5. The GTS 300 is not cheap either - in UK, it is sold for £50,000 compared with M5’s £60,000, although the gap in home country must be wider. Anyway, as supply of the Callaway engine is scarce, only 100 cars are available in a one-off production and all of them had already been sold. 

Undoubtedly, the GTS 300 is an upgrade from the regular, 335 hp GTS. Instead of using a stock Corvette LS1 engine, HSV sought help from Callaway, who undoubtedly is the expert for modifying Corvette. The 5665 c.c. engine received improved breathing, such as larger ports, lower back-pressure mufflers, elimination of airflow sensor (to reduce pumping loss), higher lift cams and lighter valves etc. As a result, the power band has been widened to cover up to 6,500 rpm where engine cut-out takes place. High speed power output is enhanced a lot while torque at below 3,600 rpm is actually reduced slightly. In other words, the engine is more linear and not as low-rev bias as before. Peak power and torque occur 400 rpm and 800 rpm respectively higher than before, that is, at 6,000 rpm and 4,800 rpm. It sounds unlike a push-rod engine ! 

The engine retains the rumble and grumble of typical American V8. Idle quality is quite unsteady due to the big port etc. Throttle response can’t match half of that of M5. Nor it is as smooth or as free-revving. The noise is deep at low speed and get serious from 4,000 rpm upward. However, it is undeniable that the 5.7-litre V8 is extremely powerful and torquey, and its efficiency even made the 4.9-litre BMW a little bit embarrassing.  

The worst link is undoubtedly the Borg Warner 6-speed gearbox. Shift quality is very poor - heavy, stiff and rubbery feel. From 2nd to 3rd is especially difficult to shift. This harm very much the otherwise remarkable driving fun. The same goes for the long-travel clutch pedal. It is these trivial things that made BMW, Mercedes and Audi so precious. HSV is still very much a car tuner. 

The good points? power aside, the handling is also remarkable, if not world-beating. Strong grip from 235/40 ZR18 tyres, powerful braking from cross-drilled ventilating discs with 4-pot calipers, fluent handling from new rear suspensions. Not really new actually. It came from the Lotus Omega, that is, basically semi-trailing arm plus a toe-control link. It fits the GTS 300 perfectly because the rear suspensions of regular Commodore were actually derived from the old regular Omega. The extra control arms keep the rear wheels toe-in slightly under even the hardest cornering, thus prevent from any uncontrollable rear-wheel slide as experienced in other Commodores or the 335 hp GTS. Now powering out of a hairpin becomes more fluent.  

Entering a corner, there’s a little bit initial understeer like any well-sorted sports saloon. Keep pushing hard, the car can power slide progressively and predictably, sometimes even 4-wheel drift is obtainable. At the limit, it is no inferior to the M5. Ride comfort is pretty good for this kind of cars. However, M5 and Audi S6 are even better. There’s still quite a lot of unsprung weight of the semi-trailing arms to cope with. 

In short, the GTS 300 has performance to amaze and has handling to match with the best European sports saloons. What it lacks is the ultimate precision and refinement found in its strongest competitors - engine, gearshift, clutch and ride. The cheap cabin may also let down those paying so much to secure one of the 100 cars made. 
 

Update - VY Commodore

- Restyled front and rear end design 
- New instrument panel and center console 
- Recalibrated power steering to improve on-center feel 
- Recalibrated front dampers 
- V8 engine added 13hp, now 315hp. 
- Recalibrated automatic transmission