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Automotive Industry

HERE COME THE 2007 DOMESTICS!

Motor, Nov 2006 by Weissler, Paul

The domestic manufacturers have several new passenger vehicle offerings on tap for 2007, as well as significant advances in the areas of performance, economy, convenience and comfort.

The 2007 domestic car nameplate lineup has important new entries from General Motors, Ford and Chrysler. Yes, there are conventional sedans such as the Saturn Aura and Chrysler Sehring, a new Mustang muscle car (the Shelby GT500) and a two-seat convertible (the Saturn Sky).

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But most significant are the crossovers-car-like vehicles with transverse front-drive, optional all-wheel-drive and SUV cues. You know such domestic entries as GM's Saturn VUE, Buick Rendezvous, Chevy Equinos and HHR and Pontiac Torrent, Chrysler PT Cruiser and Fors Freestyle. This model year look for a GM trio-GMC Acadia/Buick Enclave/Saturn Outlook-along with Fords Edge and Lincoln MKN, plus the Jeep Compass from the Chrysler Group.

The following offerings from the domestic carmakers are truly new and noteworthy:

General Motors

Much of GM s new-car product news is about Saturn. Saturn has three new vehicles-the Aura sedan, Sky convertible and Outlook, which joins VUE in the crossover category. However, some of the powertrain changes made for Saturn also apply to other GM makes.

The most important new car coming out of the GM camp may be the Saturn Aura. Although it's built on the same platform as the Chevy Malibu and Pontiac G6, it's much more upscale-nicer interior, more elegant overall appearance, quieter. It's almost like the separation between the Lexus ES 350 and the Camry V6, although not quite as far apart.

As for GM engines, the 3.5L V6 is the base Aura engine (a step up from the base 2.4L four-cylinder in the Malibu and G6). This pushrod engine gets variable valve timing, joining the 3.9L V6 used in the Malibu, G6 and Impala/Monte Carlo. The 3.9 V6, incidentally, also gets Active Fuel Management (which deactivates three cylinders during cruise), introduced last year on the Impala/Monte Carlo 5.3 V8.

The 3.6L "world" V6 (DOHC and variable intake and exhaust valve timing), which was used in Cadillac and Buick models in 2006, is the top option in the Pontiac G6 and the Aura, and the only engine in the Acadia/Enclave/Outlook crossover vehicles.

The 3.6 V6 is mated to a six-speed transaxle, the same basic transmission (with internal differences, though) that also is being used in the new Ford crossovers and Lincoln MKZ sedan. Ford and GM are in a joint venture to produce this gearbox.

What about four-cylinder engines, the several versions of the Ecotec in particular? The 2.4 version continues as noted in the Malibu and G6 but with significant changes, the most visible of which is the dropping of the engine oil cooler. GM added piston oil jets and modified the cooling system, which lowered oil temperatures enough to eliminate the need for external oil cooling. The 2.0 Super-charged version continues in the Saturn Red Line and Chevy Cobalt SS. The 2.2, with what GM calls "continuous improvement upgrades," continues in the Cobalt, Malibu, G5 (a new Pontiac-badged twin to the Cobalt) and Saturn ION. Changes to the 2.2, however, include such visually noticeable, service-related ones as a cartridge oil filter replacing the spin-on type and coil-on-plug ignition replacing the dual-coil cassettes with plug wires.

A special premium version of the 2.4 Ecotec also goes into the Saturn VUE Green Line and (some time in the spring) the new Aura-as a low-cost "mild hybrid" that promises a fuel economy boost of up to 20%.

What's a "mild hybrid"? Well, the GM "hybrid" pickups that came out last year are an example. They use a flywheel alternator/starter system and 42-volt nickel-metal-hydride battery pack. The setup in the VUE, and that's coming to the Aura this spring, has a conventional starter plus what looks like an oversized alternator but is actually an alternator/starter with a very special, seven-rib-wide belt with a unique tensioner.

A complex computer strategy determines when to stop the engine, typically when it's warmed up and the vehicle is stopped, such as at a traffic light. When the driver steps on the gas pedal, the alternator/starter operates as a motor, restarting the engine instantaneously. During acceleration, the motor also provides a small boost through the engine.

During deceleration/braking, some of the energy goes to operate the alternator to charge the 42-volt battery pack; that's called regenerative braking. The battery pack is located behind the rear seat and has a fan and ductwork for cooling.

All the electronics are housed in an underhood module, characterized by the blue wiring harness that indicates medium-voltage systems (vs. orange for high-voltage full hybrids). Like most electronics packs, this one runs pretty hot, so a tap off the front of the engine cooling system routes coolant through the electronics housing to lower temperatures.

Accessories run on 12 volts and there's an auxiliary 12-volt lead-acid battery, which also operates a conventional starter for cold starts. The vehicle's onboard diagnostics cover the hybrid system and will log specific trouble codes.

Automotive Industry

HERE COME THE 2007 DOMESTICS!

Motor, Nov 2006 by Weissler, Paul

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