“North America is a unique and challenging place, because the driving environments vary widely across the continent and customers have very specific expectations on their driving experience – especially when it comes to small cars,” said Jim Federico, Executive Chief Engineer, Small Cars. “Fortunately, the Spark was already proven in other tough markets and we had a great foundation to build on.”
To give it a more responsive and refined driving experience for North American drivers, engineers:
- Delivered more mid-range torque, for a greater feeling of power, via a 4-percent increase in engine displacement to 1.25 liters
- Increased the standard wheel size from 14 inches to 15 inches – and specified lightweight aluminum wheels, which are quieter and help enable nimbler handling than steel wheels
- Increased the “footprint” with wider 185-series tires, which provide a more confident and planted feel
- Revised the coil springs and strut/shock damping rates to give the Spark a sportier, more responsive feel – all while accommodating the broad range of American driving conditions, from urban jungles to wide-open rural highways and the almost tropical conditions of Florida to the mountains and deserts of the West
- Launched the global platform debut of variable-assist electric power steering, which delivers a more direct feel at higher speed, while helping save fuel
- Enhanced the package of features that block or absorb sound, for a quieter ride
“Making the Spark drive well in the North American environment was only part of the equation,” said Federico. “We also had to make it a little quieter for American tastes.”
The aluminum wheels play a larger role in the Spark’s refinement and complement increased sound deadening and specific body seals/baffles for a quieter ride.
More mid-range torque
The Spark’s Ecotec four-cylinder engine was developed uniquely for North America. It features slightly larger bore and stroke dimensions than versions used in other markets, giving it a 1.25L displacement vs. the standard 1.20L size. Output is rated at 84 horsepower (63 kW) and 83 lb.-ft. of torque (113 Nm) – and while that doesn’t rival the 638 supercharged horsepower of the Chevrolet Corvette ZR1, the larger-displacement Ecotec delivers more mid-range torque than the 1.20L engine. That means the Spark has a stronger, more confident feeling of acceleration especially at highway speeds, when it’s called on for passing or freeway entrance ramp performance.
A lightweight aluminum cylinder head helps keep down the vehicle’s overall weight and enhance the front/rear weight balance, while dual overhead camshafts with continuously variable valve timing optimize performance, fuel efficiency and emissions across the entire rpm band. The engine also features an efficient, coil-on-plug ignition system and long-life engine components, including 100,000-mile spark plugs, which help reduce maintenance costs during the life of the vehicle.
A five-speed manual transmission or an available four-speed automatic transmission is matched with the Ecotec engine. Each has been optimized for America, too, with the gears in the automatic revised for better efficiency on the highway, while the shifter for the five-speed was enhanced to provide a sportier, more direct feel. The five-speed also features a 3.54:1 first gear ratio, which helps provide livelier launch performance.
Chassis and suspension highlights
An inherent challenge in the mini car segment is delivering a confident and comfortable driving experience despite comparatively small dimensions – in Spark’s case, that means a wheelbase of only 93.5 inches (2,375 mm), compared with Sonic’s 99.4 inches (2,525 mm) and Cruze’s 105.7-inches (2,685 mm).
While the Spark’s wheelbase is small, it has comparatively wide front/rear tracks of 55.7 inches (1,415 mm) and 55.5 inches (1,410 mm), respectively, which give the car a wider “footprint” on the road and a confident feel behind the wheel. In fact, its track-to-wheelbase ratio is comparable to the Cruze.
Spark’s body-frame-integral structure is designed to be tight and stiff, enabling more precise tuning of the front MacPherson strut suspension and compound-crank rear suspension, for ride and handling characteristics that are responsive yet compliant and comfortable. The rear suspension, which incorporates a tubular V-beam for effective tuning and performance, is comparatively lightweight and space-efficient, enabling greater cargo and passenger space.
“With a stronger body structure, there’s less flexibility that has to be accounted for in the damper tuning,” says Federico. “The result is a more precise driving experience, with handling characteristics that better connect the driver with the road and provide an outstanding overall feeling of stability.”
Spark for North America also features the debut of variable-assist electric power steering, which will expand to other markets later. It provides a lighter feel at low speeds, such as parking, with a firmer, more direct feel at highway speeds. Electric power steering enhances efficiency, because it eliminates the conventional engine-driven steering pump, which draws energy whenever the engine is running. The electric steering gear only draws energy when the steering wheel is turned.
Electric power steering also eliminates the need for power steering fluid – and the need to dispose of it later in the car’s life.
Spark’s compact dimensions pay dividends in other areas, including a very tight turning circle of only 32.5 feet (9.9 meters). That means it can negotiate the narrowest of urban streets and turn around in them easily.
Hill Start Assist, silica-compound tires and more
Vented front disc brakes with large, 10.1-inch-diameter (256 mm) rotors are standard on Spark, along with four-channel anti-lock brakes with brake assist. Hill Start Assist is standard and helps prevent drivers from rolling when restarting from a stopped position on a hill. It allows drivers to take their foot off the brake long enough to use the accelerator and move forward.
Spark for North America also comes standard with StabiliTrak electronic stability control. It uses electronic brake and traction control capabilities to provide more precise and controlled anti-lock braking performance, impressive traction and stability.
When it comes to wheels and tires, 15-inch aluminum wheels are standard on all models (2LT model receive unique machine-finished wheels). They’re matched with wide 185/55R15 low rolling-resistance tires that use a silica compound and unique tread design for a solid road feel and greater efficiency.
The silica compound in the tires controls their flexibility, ensuring sufficient hardness at most temperatures and road conditions. That means the tires are more resistant to deformation and offer lower rolling resistance that helps increase efficiency.
One of the segment’s quietest driving experiences
Complementing the Spark’s confident ride and handling characteristics are an array of noise-abating features that block or absorb sound to give the car a refined feel:
- Thick glass, including 5-mm windshield glass and 4-mm front door glass
- Front-of-dash mat that features a dissipative material that absorbs sound
- Hood seals installed along the hood lines and between the rear edge of the hood and air induction panel eliminate potential sources of noise
- Nylon baffles and expanding foam in hollow sections of the body structure close out the passages to eliminate transfer paths of noise
- An acoustic headliner isolates and dampens interior noise for a quiet cabin
- Melt-on damping patches on the interior body structure, as well as extensive sealing throughout the vehicle, dampen sound in strategic locations.
Founded in 1911 in Detroit, Chevrolet is now one of the world's largest car brands, doing business in more than 140 countries and selling more than 4 million cars and trucks a year. Chevrolet provides customers with fuel-efficient vehicles that feature spirited performance, expressive design, and high quality.
*Courtesy of Chevrolet News United States
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