After The Turnaround
The launch of the 2007 Infiniti G35 Sedan, Nissan Altima and Sentra mark the start of Nissan’s defense of its recent gains.
Automotive Design & Production
, Christopher A. Sawyer
The 3 Series of Japan
In terms of size, performance, capability, and position within its brand, Infiniti’s G35 most resembles BMW’s 3 Series. However, whereas the BMW shares only drivetrain pieces with its larger brethren, the G35 shares not only its drivetrain, but its basic structure–the Front Mid-ship (FM) platform–with the larger M35/M45 sedan.
- In order to develop a virtual concept of the G35 for use in focus groups, the product planners ran a “Home Placement” program that put sport sedan owners in all of the competitive vehicles in the segment for an extended period. They were then surveyed in order to glean a better understanding of what’s required in a contemporary vehicle.
- The high-intensity discharge headlamps are compactly packaged at the confluence of the front fenders, “waveform” aluminum hood (it has dual latches along its leading edge to provide a tight fit) and “zero-gap” front fascia. It required a new build process. “The headlight determines the fit and orientation of all the pieces at this point,” says Randy Fior, Regional Product Manager at Infiniti, “because the parts are designed to fit together with no overlap or adjustment.”
- The optional adaptive front lighting provides a 23? sweep. When the car is stationary, the left headlight remains stationary to prevent blinding oncoming drivers when pulling back onto the roadway.
- In most dimensions, there is little difference between the G Sedan and its larger M Sedan brother. The G35 sits on a 112.2-in. wheelbase, is 69.8-in. wide, and 187-in. overall. The M has a 114.-in. wheelbase, is 70.8-in. wide, and spans 192.6-in. overall. It also sits about 2.0-in. taller, and has room underhood for a V8.
- Body stiffness is up 36% due, in part, to a modified front subframe and engine compartment, a revised rear floor, and a 16% increase in the number of spot welds.
- The 306-hp VQV6 is over 80% new, and sports a symmetric dual intake system that reduces air resistance by 18%. Block height is up 8.4 mm, while its center of gravity is down 15 mm, and variable valve timing has been added to the exhaust cam. The compression ratio is up from 10.3:1 to 10.6:1, the redline is up 1,000 rpm, and the piston skirts are no longer symmetrical. The dual exhaust system has been revised with equal-length manifolds and 25% lower exhaust back pressure.
- Bucking recent trends, the G35 makes do with a five-speed automatic transmission, but–like the BMW 3 Series–adds magnesium shift paddles behind the hand-stitched (it takes one hour to sew) steering wheel. A six-speed manual also is available.
Nissan Rethinks the Altima, Take 2
Nissan hit a homerun with the last Altima. It was, however, a flawed score–more of an inside-the-park run than a towering shot to the bleachers–that suffered from average interior quality and copious torque steer, but grabbed buyers with its unique looks and roomy interior. The Altima also was designed specifically for this market, and began Nissan’s North American turnaround.
- “One of the reasons the last Altima’s interior wasn’t as good as it should have been,” says Peter Haidos, chief product specialist on the Altima program, “is that we took money out of the original design in case it wasn’t successful. We’re not doing that this time.” The 2007 model has lots of slush-molded pieces and flush moldings, it also has padded armrests, chrome accents, a tilt and telescope steering wheel, and improved air conditioner performance. The latter, in part, is due to more upright air outlets that allow broader coverage of the upper body.
- All Altimas will be fitted with Nissan’s Intelligent Key with pushbutton start. The button is the same piece used on the Infiniti M Sedan.
- “The previous Altima used the independent rear suspension from the Nissan Skyline because it was the only IRS available to replace the beam axle originally planned,” says Haidos. It worked well. The basic design remains, but the rear radius rods and links are now aluminum.
- To quell torque steer, the front subframe was modified to allow a lower engine mounting that brings the half shafts closer to parallel with the ground and gives them a near equal angle. The front axle is now aluminum instead of steel, which saves 4.4 lb.
- Ultra-high strength steel is used in 22% of the structure, including all side-impact areas. Weight is down 44 lb., while rear body deformation is down 20% and lateral bending resistance is up 60%.
- Though slightly (0.3-in.) wider than the previous model, the wheelbase is 0.9-in. shorter, and overall length is down 2.5-in. “Female buyers wanted a slightly smaller package,” says Haidos, “and the best way to do that with all of the other changes we were making was with a new platform.” Most interior dimensions are down less than one inch, but rear seat leg room is up by 3.1-in. and trunk room increases by 3.3 ft3.
- Both the 2.5-liter QR25 inline four and VQ35 3.5-liter V6 come standard with a six-speed manual, or CVT. It is the same CVT found in the Nissan Murano, but with a new controller that has a faster processor, adaptive shift logic, and 30% more programmed algorithms. The manual is 5% lighter despite having an increased torque capacity, a 25% reduction in gear noise, and up to 36% less friction.
2007 Nissan Sentra: Finally!
The Sentra was forced to soldier on in its small, aging fifth-generation body as everything else in the Nissan lineup changed under Nissan’s initial Carlos Ghosn-inspired restructuring program. All of that changes with the introduction of the sixth-generation Sentra. Its 97.4-ft3 interior makes it 10% larger–the Sentra is almost a mid-size car in terms of interior room–while the larger 2.0-liter engine gives better fuel economy and 11% more power.
- “The car was delayed about one year because the original concept didn’t do well in consumer clinics,” says Sentra chief product specialist, Ken Kcomt. The problem was that the original rear end design looked too much like a hatchback, forcing a redesign of the car from the C-pillars back.
- While the fifth-generation car was shared with Europe (Nissan Almera) and Japan (Nissan Sylphy), the new car–which shares its major underbody components with the Renault Megane–was designed specifically for the North American market. The home market uses the same platform for the Lafesta and Serena people movers, and the U.S. will get the “mini-Murano” Rogue SUV in late 2007.
- The North American cars are wider than their counterparts, and the Rogue will be the first derivative to come off this variant of the Global C platform. “The platform is modular in that we have developed a number of rear floor pans and upper bodies that can be mixed and matched,” says Kcomt. “We can do a lot with this base.”
- The twin cam MR20DE is a larger version of the 1.8-liter found in the Versa, and produces 140 hp @ 5,100 rpm and 147 lb-ft @ 4,800. It has been tuned for low- and mid-range torque, with 90% of peak torque available from 2,400 rpm. Buyers get a choice of six-speed manual or Xtronic CVT, though “we expect 90% of Sentras to be equipped with the CVT,” says Kcomt.
- Refinement was a centerpiece of the Sentra’s design, as shown by the cradle type engine subframe, liquid-filled engine mounts, engine balance shaft, and equal-length intake runners.
- Suspension is by MacPherson struts in front and a torsion beam in the rear. Both ends use digressive shock valving that adjusts the oil flow rate based on the piston speed of the shock absorber. The rear dampers also have internal rebound springs. Separately packing the springs and shocks in the rear increased rear compartment room, as did the wider and less convoluted load floor.
- The trunk has a pair of U-shaped receptacles in the trunk floor to receive a panel that divides the trunk into two separate compartments. “You can gain access from within the trunk or the interior,” says Kcomt, “but we designed it to look like the trunk wall for greater security.” When more room is needed, the rear seat flips and folds for a flat loading surface.