Blog Auto Review

Since the Vauxhall Astra GTC shares no body panels with either the Astra Hatch or Sports Tourer, it has a unique appearance in the range, and one which has largely stayed faithful to the stunning 2010 GTC Paris concept.

"We wanted the Astra GTC to be the ultimate expression of Vauxhalls design language, and to embody our passion for the motor car," said Mark Adams, Vice President of Vauxhall/Opel design. "But we didnt want emotion to get in the way of functionality: the Astra GTC still needed to be clever, practical and affordable."

In profile, Mark and his team - a significant number of whom are fellow Brits - created tension in the GTCs shape by minimising the lines running along the body. Vauxhalls signature blade, a crisp line that sweeps up from the rocker at the front of the door, is now similar to the Insignias, but runs the opposite way to other Astras. A second line strikes through the door handle, stretching to the rear, while a third line follows the roofs profile, guiding the eye to the sharply integrated spoiler.

At the front of the car, a centreline crease is complemented by slim, eagle-eye-style headlamps featuring wing-shaped daytime running light graphics. A chrome emblem bar running across the dramatic trapezoidal grille - mounted lower than on other Astras - completes the picture from the front.

Equally dramatic is the GTCs rear treatment. Its powerful shoulder section gives the car imposing proportions and a purposeful road presence. The line from the C-pillar wraps around the tail and the rear spoiler, which in turn integrates with the roofline. LED rear lighting - optional across the GTC range - highlights the stretched wing motif created by the tail lamps.

The Vauxhall Astra GTC has a Cd figure of just 0.33.
Standard on both Sport and SRi trims are 18-inch alloy wheels, with each getting a unique design. For the first time on a Vauxhall coupe in this class, 20-inch rims are available as an option on SRi models, with 19-inch wheels a further cost option on both trims.

On the upper-spec SRi model, tinted glass is standard, while the latest generation AFL (Adaptive Forward Lighting) is optional across the GTC range.

Interior
Despite the GTCs rakish exterior appearance, unlike many of its competitors, interior accommodation and functionality have not been compromised.

Not only can the GTC accommodate five adults, but its luggage compartment provides between 380 and 1165 litres of volume - over 200 litres more than some of the competition.

In line with the current Astra, storage volume in the cabin has also been improved by 50 per cent versus the old Sport Hatch, with items like the electronic park brake liberating space around the console in SRi models.

High quality materials feature in all GTCs, as do chrome-edged instruments in deep-set binnacles that give drivers clear and well laid-out information. Standard on all GTCs are DAB stereo and USB functionality, while SRi drivers get an onboard computer and leather-rimmed steering wheel, among many other standard items.

Two new colours - Seashell and Flaming Yellow - and a selection of new materials, bespoke to the GTC, set the car apart from others in the Astra range. Morello Red, and a new premium leather trim, is also available as an option and brings with it a six-way adjustable drivers seat.

CHASSIS
The Vauxhall Astra GTCs appeal runs far deeper than its rakish lines. Unlike many three-door versions of existing compact hatches, the GTC - like the Astra Sports Hatch before it - will be a standalone model in Vauxhalls range, conceived to resonate with a more driver- oriented customer base who value the way a car handles and performs as much as the way it looks.

To do this, engineers from both Vauxhall Engineering Centre at Millbrook and Opel in Rüsselsheim have developed a bespoke platform for the GTC. Key components - such as the HiPerStruts used on the front axle - have been derived from the 325PS Insignia VXR, while significant upgrades have been made to the GTCs unique Watts link/compound crank rear end. So while the GTC line-up currently includes a broad range of engines producing from 120 to 180PS, drivers can always be assured of class-leading levels of dynamic control.

But the best chassis can only be honed through intense testing on the most demanding surfaces. Britain will be by far the biggest market for the GTC, which is why Vauxhall and Opel engineers have conducted much of their evaluation on UK roads, with their unique (and some may say diabolical) blend of undulations, cambers, rough surfaces, blind apexes and crests. The theory is this: if the GTC can work well in the UK, it will work much more effectively on other markets roads, too.

High tech front suspension boosts GTCs appeal
From the start of the GTCs development programme the target was to deliver a driver-oriented feel to the car, and one that worked well on UK roads. "Our aim was to exceed the best in class with the GTCs dynamics," said Gerry Baker, Vauxhall Engineering Centres chief dynamicist. "We also wanted to change the emphasis in steering and damper-feel from the regular Astra Hatch to a set-up that was more focused, yet still comfortable enough for British roads and drivers."

Much of the development centered around the introduction to the GTC of Vauxhalls HiPerStrut, a first for an Astra model. Based on the system currently seen on the 325PS Insignia VXR, the HiPerStrut uses the Astras existing pick-up points, but reduces the kingpin inclination angle by 44 per cent and shortens the spindle length (kingpin offset) by 46 per cent versus the MacPherson strut-equipped models. This helps prevent torquesteer - a trait of many powerful front-wheel-drive cars - allowing drivers to make more use of the GTCs performance without the steering being corrupted.

Adding the HiPerStrut has also reduced the amount of camber change on the GTCs front wheels during cornering, improving grip. Steering feel is enhanced, too, helped by a reduction the steering systems friction levels. The geometry changes brought by the HiPerStruts also mean that the GTC can be fitted with wheels of up to 20-inches in diameter.

Rear suspension revisions complement GTCs ride-height & track changes
Compared with the Astra Hatch, the GTCs ride height has been lowered by 15mm, while the wheelbase has grown by 10mm, from 2685mm to 2695mm. Both tracks are wider, too, at 1584mm (+40mm) front and 1585mm (+30mm) rear.

The Astras GTC compound crank/Watts link rear suspension system has also been revised, with bespoke roll-stiffness and roll-centre height settings for this application. The system has many advantages over a modern multi-link design, including improved packaging, greater wheel camber stiffness and reduced suspension friction. The Watts link also ensures that lateral stability is maintained at all times.

The Watts link is carried on a small cross-member attached to the underside of the car, just behind the rear wheel centre line. It comprises a short, pivoting centre link with a ball joint at each end, to which the lateral links from the wheels are bolted.

In a straight line, the set up ensures excellent stability, but during cornering it minimises lateral deflection in the same way a modern multi-link system would do. Vauxhalls engineers estimate that the linkage absorbs around 80 per cent of all lateral loadings on the rear suspension. In addition, the Watts link allows for softer bushings, which no longer have to compensate for toe changes at the rear of the car, and thus provide greater compliance and ride comfort from the rear axle.

Unique steering programme for UK drivers
Precision, Feedback & Confidence. These were the three target elements for the GTCs UK-specific steering programme. The challenge was to maintain the systems ease of use at lower speeds, but dial in a greater degree of involvement and slightly more effort at higher speeds.

The Vauxhall Astra GTC uses a rack and pinion steering system with speed sensitive assistance. But in order to provide drivers with more steering feedback, the systems electric motor is mounted directly on the steering rack, as opposed to the base of the steering column.

The key benefits of using an electric power steering (EPS) are well known. At low speeds, the level of power assistance is increased to minimise steering effort. At higher speeds, assistance is automatically reduced to ensure a high degree of steering feel for the driver. The second important benefit is that, because it does not require an energy consuming hydraulic pump and responds directly to the amount of power needed at any speed, fuel consumption is also reduced.

FlexRide enhances GTCs driver appeal still further
FlexRide, Vauxhalls adaptive damping system, will be available as a £790 option across the GTC range, complementing the significant revisions to the new models chassis. FlexRide automatically adapts to prevailing road surfaces and driving styles, providing drivers with fully optimised handling, even in the event of an emergency situation.

At the heart of FlexRide is the Driving Mode Control (DMC) which oversees and executes the systems settings, allowing the car to react to sudden changes in driving style or emergency situations. For example, if the driver needs to avoid an obstacle while in Tour mode - the softest of the three settings - chassis sensors convey this to the DMC and the dampers are adjusted in a split second.

Standard mode (the default setting) reacts in the same way as Tour, but when drivers select Sport they not only get stiffer dampers, but more steering effort, sharper throttle response and an instrument panel thats back-lit in red, rather than white. Each of these settings can be dialled in or out of Sport mode via the GTCs configurator.

British roads: the ultimate challenge for dynamicists!
Vauxhall and Opel engineers are making increasing use of British roads as a key part of their overall chassis development programmes. In the last three years, the Insignia, Astra, Astra Sports Tourer, Meriva, and now the Vauxhall Astra GTC, have all benefited from the UKs unique mix of road surfaces.

1.4-litre Turbo
Strong performance and flexibility are the core strengths of this engine, which is available with either 120PS or 140PS power outputs. Torque generation is even more impressive, with 200Nm available in both engines from just 1,850rpm to 4,900rpm, translating to a 0-60mph acceleration time of 9.0 seconds (140PS) or 10.2 seconds (120PS).

The water-cooled turbocharger, spinning at up to 200,000 rpm, is integrated into the exhaust manifold, close to the engine, for a fast throttle response. Air-to-air intercooling increases the intake charge density.

The adoption of a steel crankshaft with reinforced pistons and con-rods allows the use of a relatively high 9.5: 1 compression ratio, despite higher stresses and loads. Under-skirt piston oil cooling jets and exhaust valves filled with sodium are further measures to ensure durability under higher internal temperatures.

All 1.4 Turbo models come equipped as standard with Start/Stop, helping them achieve competitively low emissions of between 140-142g/km, depending upon wheels/tyres fitted.

1.6-litre Turbo
The most powerful engine in the Vauxhall Astra GTCs line-up produces 180PS and achieves a specific output of just over 100PS per litre. Available across the range, the 1.6 Turbo is the most powerful series production engine in its displacement class.

Its high power is matched by an impressively wide plateau of torque, with 230Nm available from 2,200rpm to 5,400rpm. With this engine, the GTC can accelerate from 0-60mph in 7.8 seconds, and on to a top speed of 137mph.

The 1.6Ts cylinder barrels are laser-etched for minimal piston friction. To withstand higher operating temperatures, the exhaust valves are filled with sodium and under-skirt piston cooling with oil jets is used. A map-based thermostat control raises the coolant temperature at low engine speeds, or under light loads, to help reduce internal lubricant friction and improve fuel consumption.

Diesel engines
All Vauxhall Astra GTC diesel engines are fitted with:
    16-valve, dual overhead camshafts
    A weight-saving aluminum cylinder head
    Threaded intake ports for exceptional swirl and burn characteristics
    Oil jet cooled pistons
    A dual-mass flywheel and a maintenance-free exhaust particulate filter

Common Rail, Multiple Fuel Injection
Operating at high pressures up to 1,800 bar, this sophisticated fuel delivery system ensures extremely fine atomisation in the combustion chamber and enables up to five injection pulses per cycle to extract as much energy as possible from a given amount of fuel. The result is exceptionally low fuel consumption and exhaust emissions, as well as reduced engine noise. Multiple injection helps iron out the strong vibrations associated with compression ignition. For example, a pre-injection during the warm-up period reduces cold-start knock to a barely perceptible level.

Variable Geometry Turbocharger (VGT)
The pitch of the vanes on the turbine wheel is continuously varied according to engine load and speed, giving an excellent throttle response, particularly during pick up from low speeds.

Improved Exhaust Gas Recirculation (EGR)
The electronically-controlled EGR system has an additional cooling function. Electro-pneumatically operated bypass flaps, controlled by the engine management system, ensure that the exhaust gas reaches a temperature suitable for combustion on its way back into the cylinder. This contributes to increased power, as well as reduced emissions.

The diesel line-up comprises:

1.7 CDTi
Available in two states of tune, providing either 110PS and 280Nm of torque, or 130PS and 300Nm. Combined cycle fuel consumption for both is 62.8mpg with standard wheel rims fitted, and each achieves 119g/km. Despite being the most frugal models in the range, the 1.7 CDTis allow the GTC to accelerate to 60mph in either 10.0 (130PS) or 11.0 seconds (110PS). In 2012, an ecoFLEX model using a version of this engine will be available in the UK with emissions of just 109g/km. Start/Stop is fitted to all 1.7 CDTi models as standard.

2.0 CDTi
The 2.0 CDTi packs 165PS with an exceptionally strong 350Nm of torque from just 1,750rpm. This helps it achieve a 0-60mph time of just 8.4 seconds and 50-70mph in 6.4 seconds, together with a combined fuel consumption of 58.9mpg and emissions of just 127g/km (18 & 19-inch wheels fitted). Vauxhalls Start/Stop system is fitted to all 2.0 CDTi models as standard.

Hydraulically-damped mountings for improved NVH performance
All powertrains are bolted in position via hydraulically-damped mountings that minimise vibration through the body structure. Adaptor plates enable the same four fixing points to be used for all applications, two on the front sub-frame and one on each longitudinal beam.

The fuel supply system uses an electric pump and filter mounted in the 56-litre fuel tank, which is located low under the rear seat for optimal weight distribution and crash impact protection.

Start/Stop reduces emissions, improves urban fuel consumption
Vauxhalls Start/Stop technology, which is available on all 1.4 Turbo, 1.7 CDTi and 2.0 CDTi engines, is highly efficient and helps to reduce emissions. As soon as the driver selects neutral, the Start/Stop system is activated and the engine unit cuts out automatically. The rev counter needle then assumes the Autostop position. When the driver wants the engine to start up again, he/she just selects first gear and departs. A powerful battery ensures that there is no delay in the engine starting up again.

For safety reasons and to ensure the comfort of passengers, the temperature and pressure functions of the brake power assist unit remain active during the Auto-Stop phase of the Start/Stop system. When necessary, for example during slow city traffic, the driver can manually de-activate the system, using the "eco" switch.

Transmission
Six-speed manual gearboxes, offering a wide spread of ratios and a tall, fuel-saving top gear, are standard fit across the entire range. All gearboxes include triple cone synchronization on first and second gears for easy engagement, and a synchronized reverse gear.

A six-speed automatic gearbox is also available on 1.4 Turbo 140PS and 2.0 CDTi 165PS engines.

MARKET
The all-new Vauxhall Astra GTC replaces the successful Astra Sports Hatch, and will lay down the gauntlet to VW Scirocco and Renault Megane Coupe when it appears in showrooms at the end of November 2011 with a heady mix of dynamic excellence, dramatic design and competitive pricing.

Closely based on last years stunning GTC Paris concept, the Vauxhall Astra GTC enters the UK market - the biggest in Europe for this model - priced from just £18,495, nearly £1,350 less than the basic VW Scirocco. But even in entry-level trim, the Vauxhall Astra GTC adopts the sophisticated HiPerStrut front suspension derived from the Insignia VXR, offering precision handling and unmatched stability.

The third body style to come off the Astras Delta platform (following the Hatch and Sports Tourer), the only exterior design elements the GTC shares with its siblings are door handles and the roof aerial - even the wheelbase and tracks are different. Brit, Mark Adams, Vauxhalls Vice President of Design, has aimed to create a car that looks like its been plucked from the class above, with its low, wide stance and simple, yet rakish lines.