Extended Test
Lexus GS450h
Also read our Behind the Wheel Blog here
The logic of applying fuel saving hybrid technology to small cars first has never really sat well with yours truly.
Small cars by definition use less fuel. Getting better than 5.0L/1000km is far from an impossible task for a conventional small car, yet it's only now with the impending arrival of the new Prius that hybrid tiddlers are bettering the 4.0L/100km mark. On a proportional basis 25 per cent is impressive, but you're still only saving 1.0L/100km.
It's larger cars and SUVs surely that can benefit most from this sort of electrickery. There's some serious carbon-thingies to be saved in driving a 8.5-9.0L/100km car rather than a 15-17L/100km soak. Plus it's larger cars that can better wear the cost imposte of expensive drivetrain duplication, batteries and the like.
So why then is there still just one brand with large hybrid sedans on the market?
To mash the English language, the Lexus GS450h is almost unique in the Australian marketplace. Though it shares the showroom with a medium-sized hybrid softroader, until its big brother LS600hL happened along last year (more here) it was the solus large hybrid passenger car on sale.
Indeed while there's a likelihood Mercedes-Benz's S-Class Hybrid will make it to Australia next year (and perhaps even a Porsche Panamera with batteries), even if that happens on time, the GS will be the only large hybrid sedan even close to being affordable for some time to come. Affordable in relative terms, that is...
Such is the pace of automotive change, it surprising that the 450h is still in a class of one. Introduced in May 2006 as a technological flagship to Lexus GS range, it's aimed at the likes of BMW's 5 Series, Mercedes-Benz E-Class and Audi's A6.
Launched alongside conventional V6 and V8-engined models it was originally priced at $121,990 -- about $10K above the GS300 and $15K below the GS430 V8 model. Unlike the Euros, options offered were few. Not that the 450h needed much -- like most Lexi, it comes loaded.
More recently -- last March in fact -- the 450h scored a minor facelift but no mechanical changes (at the same time the V8 model was beefed up with a new 4.6-litre engine -- more here). It's this tweaked $124,900 that we've added to our Carsales Network fleet.
Why? Well simply we want to see whether the commonsense viewpoint that a large hybrid should make sense, translates to the real world.
A QUICK TECHNICAL OVERVIEW
Way back at the 450h's launch we published a detailed technical rundown on the car (more here). In short, the 450h is not powered by a 4.5-litre engine as its badge implies, but rather a petrol engine/electric motor combination that Lexus says delivers comparable or better performance than, say, a 4.5-litre V8.
Under the bonnet is a fuel-injected 3.5-litre V6 coupled with a 147kW/275Nm electric motor-generator and clever constantly variable transmission (CVT) and motor-generator unit. The car is conventional rear-wheel drive and the auto offers a semi-sports sequential mode.
Rated at 218kW and 368Nm, the V6 is Lexus' most advanced V6 to date (at least until the new RX450h arrives). Combined with the electric powertrain, the V6 not only powers the car, but also charges the battery pack when required. Of course, regenerative braking (true regenerative braking -- not the quasi system of alternator cut-out proffered by BMW and others) is also used to boost power reserves when coasting, or indeed, braking.
The driver needs do nothing to manage this energy flow. Like its little front-wheel drive cousin, the Prius, the GS450h's systems do this automatically.
And it does it well... As we said in our initial launch review (which took place at Bathurst's Mt Panorma circuit no less): "By exploiting the instant 275Nm torque of the main electric motor to move the car off the line then feeding the petrol engine's output through the continuously variable transmission, Lexus has made the switch between power sources imperceptible while eliminating wasteful torque-converters and clutches. Depending on the charge in the battery pack, the petrol engine supplements the electric motor only when required."
For the record, the GS's battery back is fitted twixt the rear seat and the boot and weighs around 70kg. Overall the car's mass compares closely with 'conventional' sedans of the same size.
Though the battery significantly eats up space in the boot (the fuel tank's also a tad smaller), as we've already experienced it's not this that hurts the GS's carrying capacity, rather the size of the boot opening -- a problem on even the petrol models.
Where to from here?
Lexus specifies the maximum combined output of the GS's petrol and electric drive systems equates to 254kW and claims a zero-100km/h acceleration time of 5.9sec. Neither are numbers to be sneezed at -- especially as the big hybrid also claims a combined fuel economy figure of 7.9L/100km. Lexus does not publish combined torque figures, however states the electric motor offers 275Nm.
By way of comparison, the GS300 engine output and acceleration specs are 183kW and 7.2sec respectively and the new GS460 boasts 255kW and 5.8sec. Along with these numbers come the petrol GS's fuel economy figures -- 9.8L/100km and 11.0L/100km respectively.
It's the real world comparison against these numbers, and the day to day driving experience we're interested in learning more about.
Back in August 2006, we found that the efficiency of the standard Lexus V8 was the biggest hurdle in getting the 450h to make sense -- in a short back-to-back comparison there were at times less than 2.0L/100km difference between the two. It'll take us a while to revisit the subject but better late than never...
Also read our Behind the Wheel Blog here
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