Hyundai introduces Veloster

  • 03-Oct-2011 07:17 EDT
aei-veloster-ext.jpg

Veloster third door is on passenger’s side, with its handle “hidden” in black trim near window's top.

The new Hyundai Veloster coupe is obviously something different from a styling standpoint, and a second rear-access door on the passenger’s side just adds to that distinction. Although it has some derivative aspects, the new car isn’t a custom body on an existing sedan. It’s a low-priced ($17,000-23,000 range) model with new technology, including Hyundai’s own DCT (dual-clutch transmission).

Hyundai Motor America CEO John Krafcik told a vehicle introduction media audience that the Veloster was not a spinoff, but that it shares dimensional mounting points with the Elantra. The engine is the new 1.6-L gasoline direct injection four cylinder rated at 138 hp (103 kW) and 123 lb·ft (167 N·m) that is also installed in the new Accent. Both cars are transverse front-drive, but the application in the Veloster has hydraulic engine mounts.

Although recent Hyundai introductions (Sonata hybrid, Elantra, and Accent) have carried 40 mpg EPA fuel economy ratings for all models, the Veloster falls slightly short. The six-speed manual transmission does hit the magic number (28 mpg city/40 mpg highway), but the DCT, which Hyundai calls EcoShift, is rated at 29 mpg city/38 mpg highway.

The coupe is built on a 104.3-in (2648 mm) wheelbase and has a 166.1-in (4217-mm) overall length. It is not especially powerful or quick, with 0-60 mph (0-98 km/h) in just under 10 s, but it is intended to be nimble. The electric power steering requires just 2.88 turns lock-to-lock, has a relatively quick ratio of 14.2:1, and the car’s turning circle diameter is 34.1 ft (10.4 m).

Because the Veloster is aimed at a younger audience, considerable attention was devoted to telematics. A 7-in center stack touchscreen is standard, as is Bluetooth, Hyundai’s Blue Link infotainment system, and Pandora internet radio compatibility. If a buyer orders the Technology Package, the car also is equipped with a 115-V outlet for a game console such as a Microsoft X-Box. The standard infotainment system has available all the expected bells and whistles (see http://www.sae.org/mags/aei/9433), and near-term upgrades are likely to primarily be in the area of compatible apps.

The DCT hardware was developed in Korea, and in 2009 the job of calibration was assigned to the U.S. engineering staff under supervision of Jerome Gregeois, a powertrain engineering manager. It’s a six-speed dry-clutch design, vs. the wet-clutch unit used by Volkswagen, but similar to the type in the Ford Fiesta.

The wet clutch has better thermal performance, so it’s used with higher-performance engines. However, oil circulation through the clutch assembly does result in a parasitic loss that could have some effect on fuel economy. A wet clutch also requires special oil (vs. the ordinary manual transmission fluid in the EcoShift) and robust oil sealing.

The layout is a conventional two-shaft with 1st, 3rd, and 5th gears on one shaft and 2nd, 4th, and 6th on the other. Because the next upshift is already pre-selected on the other shaft, a DCT normally executes upshifts very quickly and there is virtually no drop in torque throughput.

So why didn’t the DCT calibration hit the magic 40-mpg highway number even though the city number is one mpg better than the manual (29 vs. 28)? Shouldn’t the DCT also be capable of calibration to deliver equal or perhaps better highway fuel economy than a manual transmission?

In the real world, it should be as good, Gregeois said. But to actually get the 40-mpg number for the window sticker Hyundai would have had to make an ECO calibration for 40 mpg the default. However, this is Hyundai’s first DCT and it was cautious about the approach, noting that U.S. buyers of DCT-equipped cars often don’t like some of the shift qualities.

The calibration philosophy was to avoid attempts to replicate the feel of a conventional automatic transmission because the engineers felt the results could lead to more questions from buyers, Gregeois added. A DCT doesn’t have a torque converter so there’s no significant damping (although a wet clutch provides some, the Hyundai design has only a mechanical damper to provide a small amount). Further, dry clutch DCT calibration has to keep slippage of the clutch to a minimum to maintain its durability.

DCTs require more calibration finesse on skipped-gear hard downshifts than normal upshifts because, with the pre-selected gear arrangement of the DCT, the next gear on upshifts is already engaged. All that’s needed is to engage the appropriate clutch with a minimum amount of slippage. So Hyundai took an approach that accepted most of the crisp shift character of a DCT on hard acceleration, while avoiding harshness on a gentle launch.

With the chosen calibration, the upshifts on mild acceleration are smooth, taking advantage of the pre-selected gear arrangement of the DCT. The first clutch full engagement is at 600-1000 rpm on launch at a road speed of about 7 km/h (4 mph). On heavy-throttle acceleration, the engine is allowed to rev to nearly 2000 rpm to produce more torque before the clutch is fully engaged at a road speed about 13 km/h (8 mph). The overall engagement bias is for a combination of clutch durability and driveability, Gregeois told AEI.

The Veloster is a compact, with a total EPA interior size of 105.3 ft³ (2982 L), of which 15.5 ft³ (439 L) is the cargo volume, making it the largest in a competitive class that Hyundai says includes the Scion tC, Mini Cooper/Clubman, VW Beetle, and Fiat 500. The Beetle at 100.5 ft³ (2846 L) and Scion tC at 103.1 ft³ (2919 L) are also compacts; the Mini and 500 are subcompacts. Veloster curb weight is 2584 lb (1172 kg).

The suspension is a conventional McPherson strut front, coil spring with torsion beam rear, but with a Hyundai “twist.” The torsion beam itself is an inverted V with the 23-mm (0.91-in) stabilizer bar routed through the V and retained at the end of each arm. This not only is a packaging innovation but Hyundai says it braces the arms for greater stiffness and helps control body roll.

The fully-dressed car body was benchmarked for torsional rigidity against the European Volkswagen Scirocco, called by Hyundai a comparable car, and it scored higher: 31 Hz vs. 23 Hz for the Scirocco. Some two-thirds of the Veloster body content is in high-strength steels, certainly a key factor. The higher the torsional rigidity, the less the body twists during handling maneuvers and therefore the more accurately the car can respond to steering inputs.

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