Holden Astra prototype 2017 Review

Holden Astra sedan prototype
First drive
Gippsland, Victoria

Driving a development version of a new car is always a risky exercise for both the car company and the media involved.

From the car company’s perspective, it is handing out a hand-built squillion dollar prototype that journalists might either trash physically or in their stories.

After all, the cars aren’t built to offer production levels of noise and vibration dampening, nor to present an accurate rendition of exterior and interior design and features.

Take the Holden Astra sedans motoring.com.au sampled last December. Dubbed Integration Vehicles, or IVs, these German-built prototypes have been in Australia for around 12 months. They are about 65 per cent indicative of the final production vehicle, so the exteriors are daubed in black and white camouflage and the ungrained plastics inside – where not hidden under covers – are held together with race tape.

But Holden wasn’t letting us loose in these two cars – and providing an Astra hatch as a comparison drive – so we could draw hard and fast conclusions about the complete package the new Astra sedan will present when it goes on-sale in May.

No, the idea was to get inside the testing program designed to localise the Astra for Aussie conditions. To do that we drove on public roads that Holden regularly uses in south-western Gippsland and then visited the super-secret Lang Lang proving ground for some, erm, spirited driving, on closed roads.

But just to backtrack a little. As we detailed last January, the Astra sedan is actually the new-gen Cruze everywhere else in the world.

It will go on-sale here in three specifications, all powered by the same 110kW 1.4-litre turbo-petrol four-cylinder engine that the Astra R hatchback gets. Transmission choices are six-speed manual and six-speed automatic.

Like the Astra hatch, the sedan rolls on the stiffer and lighter new D2XX architecture, albeit with a 38mm longer wheelbase at 2700mm and without a Watts linkage locator for its beam rear axle that the hatch gets.

The other sizable omission is autonomous emergency braking. It’s simply not available in any Astra/Cruze sedan specification. Despite that Holden is forecasting a five-star result from independent crash authority ANCAP.

When investigation of the new Astra sedan began a few years ago, Holden’s engineers quickly realised they wanted to retune the chassis, refine some driver assistance systems and modify some automatic transmission calibrations.

This required work both here and overseas. The D2XX architecture’s development homeroom is at Opel in Germany, but there were also trips to a General Motors development track in Spain and to GM in Korea, where the sedan is built for Australia and the final engineering details were sorted. Suppliers such as TRW, S&T Motiv and Bosch were also involved along the way in the tuning process.

“There have been lots of fingers in the pie, this is a really good example of global engineering,” said Holden vehicle development boss Jeremy Tassone.

Of course, motoring.com.au has already sampled the Astra sedan, albeit as a Chevrolet Cruze in the USA in January. But that chassis tune was clearly not what Holden wanted in Australia.

“It was key for us the [Astra] hatch and sedan drive similarly, albeit with a slightly different flavour,” explained Tassone. “Astra has a real trademark as far as its handling, its capabilities on-road and its refinement and we wanted to hang on to that.

“But the sedan customer is a slightly different customer who enjoys a bit more comfort in their car and that was the challenge.

“With that in mind we were able to do a full local and regional chassis tune on the sedan.”

The Australian chassis tune, developed at the Lang Lang proving ground near Melbourne, has now been adopted for the Cruze sedan across the General Motors International region, which encompasses the Middle East, south-east Asia, South Africa and the Asia-Pacific.

Refining the tune of the electric-assist steering was the priority for the Australian engineers. Right-hand drive is an obvious change from Germany, but more relevant than that are road conditions.

“We have got lots of different types of road surfaces from flat or even negative camber on some multi-lane highways or freeways, right through to very highly cambered single lane carriage ways where a standard system just left to its own devices would tend to follow the camber of the road,” explained Tassone.

“Our term for that is leads or pulls. The car pulling left is probably the biggest complaint that we get. So, within the EPS we have the opportunity to have leads and pulls compensation.

“But with the base tuning that was done out of Europe none of that compensation was enabled. So, to enable that we had to basically start from scratch with a new steering calibration for the hatch and then modify that for the sedan,

“The focus of the sedan was to get that nice direct, balanced and responsive feel the Astra hatch has but just dial back the sportiness a little bit and give it a bit more comfort and adjust the weight a little bit.”

The steering could be retuned via software, but the suspension required swapping various shocks and springs to reach the target set by lead vehicle development engineer Rob Trubiani – best known publicly as the Holden driver who took on the Nurburgring in a VF Redline ute in 2013.

“Rob uses this term breathing,” explained Tassone. “He likes the car to breath and soak up the bumps, use the suspension travel but do it in a controlled manner.

“So that’s what we are talking about with the primary body control. That is what we have really gone for, a nice even-ness between the front and the rear of the car.

“We just tried to get a bit more comfort into this car without losing that DNA of the handling traits that an Astra has.”

Holden also delved into the torque vectoring, stability control and trailer sway control tuning of the Astra sedan. Again, local conditions drove the re-tune.

“Europeans are very focussed on ice and snow but when it comes to broken bitumen and gravel and that sort of thing, I think the quote I heard was ‘Germans slow down on poor roads’,” recounted Tassone. “Obviously, we don’t always have the opportunity to do that.

“We wanted the car to be nice and linear in its responses and not get too loose and act too aggressively.”

The automatic transmission calibration flowed on from work done with the locally-manufactured Cruze in terms of tuning uphill and downhill modes and shift stabilisation, which reduces flare.

The two Astra IVs we drove were set up slightly differently. The ‘chassis’ car had the latest suspension and steering settings and rolled on 16-inch 205/55 Hankook Kinergy Eco tyres. The ‘electrical’ car, which was focused on things like radio and sat-nav tune, didn’t have completely up-to-date chassis settings and was shod with 18-inch Kumho Ecsta 225/40 rubber.

But despite those differences, there was a fundamental driving similarity offered by the two cars. They definitely tended to give up a little bit of body control and flat cornering attitude compared to the hatch in return for a little more compliance in the ride.

Steering was also that little less focussed and not quite as direct as the hatch. The rack in the sedan is slightly retuned to feel the same from variant-to-variant despite the different tyre sizes being used.

No doubt, the cars were well controlled and behaved on the public road. They even stayed composed when being pushed very hard on Holden’s ‘Hill Road’ handling course that included steep, hard braking, flat-out uphill acceleration, broken road edges and some off-camber corners that required good car balance and delicate steering inputs.

The 1.4-litre engine has to be worked to its maximum in such circumstances. It’s a pity that the 1.6-litre from the hatch isn’t also available. Having said that it’s doubtful many Astra sedans will ever be driven that hard.

Perhaps more relevant day-to-day for many owners is the generous-rear seat-room and large 400-litre boot (approx) that is enabled by the wheelbase stretch.

So, at the end of a nervous few hours for Holden’s engineers their babies were handed back unscathed. It’s impossible to be definitive given the crudeness of some aspects of these IVs, but our experience indicates the Astra sedan is another worthwhile localisation effort following on from the Barina Spark, Colorado and Astra hatch.

Tassone says this consistency of feel is about making all Holdens “great to drive”.

“Giving every driver a car that is confident and engaging to drive and they feel relaxed and fresh at the end of the drive - that is what great to drive means to me.

“That’s what we are trying to do to every single car and what we are really striving for.”

Holden Astra LS prototype pricing and specifications:
Price: $20,990 plus on-road costs (estimated)
Engine: 1.4-litre four-cylinder turbo-petrol
Outputs: 110kW/245Nm (m) 240Nm (a)
Transmission: Six-speed manual/automatic
Fuel: 5.9L/100km (est)
CO2: 136g/km (ADR combined)
Safety rating: TBA (Five star ANCAP forecast by Holden)