2017 Holden Colorado and Trailblazer engineering development drive

It's not uncommon for members of the public to spy pre-development vehicles being driven around the traps by manufacturers ahead of their launches. It's less common when the vehicles being driven are not produced in Australia. And, it's even less common when we're allowed to drive them.

We had the chance to join the Holden engineering team, the team that has been essential and core to the development of the new 2017 Holden Colorado and 2017 Holden Trailblazer — or the Chevrolet S10/Colorado/Trailblazer as they are known in other markets.

Our two-day journey began at Holden's top secret proving ground in Lang Lang, where all of our telephones and (strangely) laptops were inspected, with their cameras all covered in non-transparent stickers.

Part of the reason security is so overzealous at the Holden proving ground is that the team there works on products from all over the world. While most secret things are hidden away when the team knows that media is coming, we spotted a raft of mutilated, inbred vehicles that we unfortunately can't speak of.

At the time of this two-day event, most of the key details were yet to be released. Additionally, no media in the world had driven the new Colorado or Trailblazer. So it was a unique opportunity for the small handful of media in attendance to become immersed in the process and the vehicles.

There were some familiar faces amongst the Holden team, with a number of engineers also working on products that we know and love, like the Holden Commodore and Spark.

Over the course of two days, we had access to a fleet of vehicles that included the Colorado and Trailblazer. While they may have looked normal from both the inside and outside, they all represented different stages of the development program.

The Trailblazer, covered in camouflage, was a handbuilt Integration Vehicle (IV). It was assembled in Brazil by the core engineering team behind the project. While it may not look like it, the car is worth hundreds of thousands of dollars and represents one of the first engineering prototypes for this project.

Seen wearing camouflage in the photographs, the covered Colorado was a pre-production vehicle. It was one of the first cars down the production line and built to ensure tooling and processes are correct for future iterations of production vehicles.

The rest of the vehicles then range through different development stages to the red Colorado, which is part of the Captured Test Fleet (CTF). It was one of the latest vehicles to roll down the production line and is very close to the final product with respect to build.

Holden's local team of engineers had a total of nine CTF vehicles and two pre-production/hand-built vehicles at their disposal for local ride, handling, steering, stability control and off-road tuning, with a great deal unique to Australia and some of the Australian changes made permanent for the global model.

It was interesting to see the great deal of difference between the vehicles in terms of build and materials. For example, the Trailblazer had several different seat stitch patterns throughout the car. It also featured some very roughly cut plastics around the door trims — these items were still being designed and signed off as this car was being built by hand.

In fact, that car was torn down and reassembled several times throughout the development program to ensure everything was right and that any changes made were working.

The main goal with the new Colorado and Trailblazer was to flip this on its head. The team didn't have the luxury of starting from a clean slate like Ford did with the Ranger, Toyota with HiLux or Nissan with Navara. But, they were determined to make the most of it, with a joint program involving GM Holden, GM Brazil (where the development homeroom is situated) and GM Thailand.

Before we look at the driving we undertook during our two day stint, let's look at the huge amount of work that has gone into the new Colorado and Trailblazer models. We'll cover these using separate headings to make it easier to understand.

Steering

If you've ever driven a current Colorado or Colorado 7, you would have enjoyed the extra muscle mass earned on your arms following any city or low speed driving. The hydraulically assisted steering was heavy and contained what felt like 20 turns lock-to-lock.

That has all, thankfully, changed. The steering has been updated with an electrically assisted steering rack that offers variable resistivity as vehicle speeds increase or decrease. At low speeds it's lighter, while at high speeds it firms up to offer greater feel.

Throughout the steering range there is much more feel and it's easier to use across all speeds. Also gone is the dead feeling about centre.

Some of the changes include reducing the amount of turns lock-to-lock from 3.9 to 3.29 and changing the steering rack from one with 41mm of rack travel per revolution to one that offers 48mm of rack travel per revolution. This effectively means less steering input is required to effect the same amount of turn, making the steering more 'car-like'.

The new system was co-developed by Holden at the Lang Lang proving using an automated robot that controls the steering rack. The purpose of the robot is twofold — firstly, it can enter continuous and accurate steering inputs for benchmark purposes, but secondly, it's also used to evaluate the stability control.

The incredible robot can flick the wheel 1-2 turns in each direction to unsettle the car to ensure the stability control works as it should. It's quicker than any human could ever achieve and is mandatory for Holden to achieve compliance in the stability control test.

Chassis and driveability

You will genuinely not recognise the Colorado and Trailblazer — especially when driving the old and the new back-to-back. The engine feels linear and there is no longer a dull drone or heavy vibration through the chassis under acceleration.

That's because Holden spent a huge deal of time concentrating on improving driveability — especially noise, vibration, harshness and handling.

Firstly, the suspension has been completely reworked thanks to revised spring rates, the introduction of digressive front and rear shock absorbers along with an increase in size to the front stabiliser bar to 34mm, which represents an increase of around 15 per cent.

While we can't delve into too much detail (that will come when we drive the final product at the official launch), we can say that the ride and handling has been massively improved.

Rob Trubiani, Holden's vehicle dynamics engineer, is the man responsible for making every Commodore since the VT drive the way that it does — including one of our favourites, the SS-V Redline. Rob's one of few engineers in the GM world that is accredited to drive on behalf of the company at the Nurburgring and even owns a record for piloting a ute around the Nurburgring in just under 8 minutes and 20 seconds.

So it's fair to say that Rob's credentials are certified. Rob took us for a flying lap around Holden's ride and handling track at Lang Lang. His impressive skills aside, Rob demonstrated just how settled the Colorado feels at its very limits. Mid-corner bumps were a non-issue, likewise progressive corners at speed.

To ensure we were properly sold on the Colorado's dynamics, Rob took us out on the high-speed bowl. He sat the car at around 160km/h on the third banked lane and demonstrated that the car uses centrifugal forces to hold itself on the third upper lane — with no hands on the wheel.

Things were turned up a notch when Rob switched off the stability control systems and bumped the speed up to 180km/h. He then demonstrated a sudden lane change, at 180km/h, from the third to the second lane... without warning! We were blown away... it's almost inconceivable to imagine, but even at these unrealistic speeds, the car sat flat and remained perfectly stable.

Back at civil speeds, we had the chance to feel some of the changes beneath the skin. Helping smooth out the body during acceleration, Holden and GM engineers employed a set of new engine and transmission mounts, in addition to a unique final drive ratio for Australia to help with towing (on vehicles with the six-speed manual transmission).

But the greatest improvement is actually an item that will rarely, if ever, be seen. And it's unique to the six-speed automatic. It's called a Centrifugal Pendulum Absorber (CPA) torque converter. And, it's a device only really seen on more premium vehicles to prevent any chassis vibration under load.

This experience was quite prevalent on Colorado and Colorado 7 with automatic transmissions and it completely transforms the driver under load. The CPA acts to divert any vibration forces away from the driveline and chassis and instead absorbs them. This means that instead of sending vibrations through the cabin and chassis, they disperse through the CPA.

Other changes under the skin include the introduction of shear body mounts, new tyres aimed at reducing road noise, a relocation of the balance shaft to reduce vibration, aerodynamic changes to reduce wind noise, injector insulators, a metal timing cover and an oil pan insulator.

Safety

A rear-view camera is now standard across the Colorado and Trailblazer ranges (except cab chassis, where it can be fitted as an option), while select models will receive an active safety package that includes forward collision alert (in the form of a flashing red LED light and audible warnings), lane departure warning, front and rear parking sensors, along with a tyre pressure monitoring system.

Structural improvements have also been made, in addition to the inclusion of a driver-side knee airbag, increasing the total airbag count to seven.

With these additions, the Colorado and Colorado 7 should be able to achieve a five star ANCAP safety rating again.

The drive

Again, we can't go into detail on how the car drives. We can only talk about how these pre-production vehicles drove and the things we were able to experience.

Our first stint around Lang Lang was in the Trailblazer around Holden's off-road circuit. This included a simulated river crossing to test wading depth, along with a steep incline to test hill holding and traction, and a steep descent to test the hill descent control program.

As expected, the Trailblazer passed with flying colours. Unlike some of its competitors, both the Colorado and Trailblazer don't feature lockable rear differentials. Instead, both vehicles use a helical Limited Slip Differential (LSD), in addition to traction control to apportion torque between the rear wheels.

Normally this is a poor solution to the issue. But, over the course we drove, it actually worked quite well. An offset group of concrete blocks designed to have a rear wheel in the air (a situation that would normally require a rear differential lock) was used to show us that with minimal fuss, the four-wheel-drive system was able to transfer enough torque to the tractive wheel to get moving.

Following this test, we connected a large trailer to a Colorado. Weighing in at around 2000kg, the braked trailer had most of its load right at the back. This is the ultimate worst case scenario for the 'death wobbles' — this happens when a driver is overly aggressive with steering inputs with a trailer.

The countered weight of the trailer can cause the rear of the car to then uncontrollably swing and eventually cause the vehicle to spin out. Both the Trailblazer and Colorado are fitted with trailer sway control. This technology employs the vehicle's stability control to immediately stop the 'death wobbles'.

To simulate this, we accelerated to around 100km/h and deliberately performed an emergency lane change. Full disclosure — I've never done this before with a trailer because it's a totally stupid idea, but I can see how and why somebody could, and would need to, do it.

As we corrected into the next lane (simulating a swerve around another vehicle on a highway), the rear end started to slip out and in a matter of moments, the stability control aggressively intervened and straightened everything up. It was absolutely amazing and was even more incredible when watched from the outside.

With this system inoperable, the trailer would have caused the car to jackknife violently and with that much weight and speed, it could be the final moments before a rollover or a nasty accident. It's very impressive technology and an absolute must if you're planning on towing and touring.

Our final exercise at the proving ground was to try the robotised Colorado. The system uses a robotic arm that controls steering inputs from the passenger's seat. Driving the vehicle up to 80km/h, the driver then uses a joystick trigger that instructs the car to input over 180 degrees of steering lock in each direction suddenly.

As we mentioned earlier, this is quicker than any human could do and is designed to ensure the stability control operates correctly. It's a totally unnatural feeling when you look at the size and height of the Colorado from the outside. It doesn't look like it should be able to change directions suddenly at 80km/h.

We left the proving ground for a road loop through to the Yarra Valley in the fleet of vehicles. The roads included some windy roads, in addition to a challenging off-road section, originally used by the team to calibrate the four-wheel drive system.

It's on public roads that the development and pre-production vehicles really shone. We were impressed with their composure and are looking forward to testing the final product in the coming weeks.

The significance of the Colorado and Trailblazer development program is huge. Holden's local engineers worked closely with their Brazilian counterparts to develop these vehicles, with drive programs across the world. It's also significant because the '100 per cent buy-off ride' was managed and run by Holden in Australia.

This final test of the product in Australia before sign off was attended by GM employees from Brazil, Thailand, India, Europe and the USA. With local testing accounting for around 100,000 combined kilometres, the international team was able to experience Australian conditions first-hand, allowing them to get a better understanding of why the local team demands some of the strange things that it does.

We are looking forward to driving the final product in the coming weeks. If it's anything like the pre-development samples we tested, the Colorado is likely to perform much better than it did the last time we put it up against its competitors.

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