New Honda Fit introduced with "Earth Dreams" engine, CVT, new body construction

  • 16-Apr-2014 08:52 EDT
aei-fit exterior.jpg

The restyled Honda Fit is shorter than previous model but has more rear legroom.

Advanced engineering used to trickle down from premium models, but the need to provide appealing fuel-efficient vehicles that help car makers meet U.S. Corporate Average Fuel Economy standards results in a comparable effort at the entry level too. As demonstrated by the 2015 Honda Fit introduced at the 2014 New York Auto Show, the specific engineering may be different, but it reflects innovative approaches to satisfy customer demand.

The car gets Honda's latest engine technology, the "Earth Dreams" approach in the 1.5-L four-cylinder, that with a CVT (continuously variable transmission) takes the fuel economy over the magic 40 mpg EPA highway mark. The rating is 33 mpg city/41 mpg highway, vs. 27/33 for the previous model with a five-speed automatic.

The engine, a long-stroke—73 x 89.5 mm (2.87 x 3.52 in) design, is rated at 130 hp (97 kW) and 114 lb·ft (155 N·m), an 11% increase in power and 7.5% boost in torque. The new engine has dual overhead cams and larger valves, vs. the single cam of the previous engine. It has direct injection, variable intake lift, and variable intake and exhaust cam phasing.

The center of the piston crown has a depression to create a well for the fuel injection and ignition, and a new, smaller spark plug is used. The higher performance dictated steps to improve heat transfer within the block. So the pistons are oil-cooled by jets, and aluminum lips from the block cover the top ends of the iron cylinder liners.

To offset some of the engine design features that increase weight, other changes for the Earth Dreams execution include a lighter crankshaft, achieved by reducing the number of counterweights from eight to four, and relocating them so smooth operation is maintained. And the bearing cap bedplate was replaced by individual caps, another weight-saver.

The CVT is adapted from the Civic, but retuned for the Fit. The Fit version has seven artificial shifts, plus an S mode with paddle shifters, so ratios can be "engaged" manually, although the CVT will "shift" to prevent overrevving or lugging.

The five-speed manual has been replaced by a six-speed, which has the same top-gear ratio of 0.727:1. Some 15% of Fit buyers pick the manual, so it's a significant offering, and as a result, there were steps to improve its appeal. The shift stroke was shortened, the shift feel was smoothed by stiffening the linkage, and because the internal cable sliding resistance was reduced, the completion of the shift produces a crisp feel.

New platform, body construction

The Fit is on a new platform and it's an innovative design. The car consists of a frame-like section of structural members including a floor pan. An overlay section of body panels is welded and bolted to the "frame" to complete the structural package. This approach, perhaps somewhere between monocoque and spaceframe, though not equivalent to either, provides improved body rigidity without a number of the stiffeners previously used, Honda said, and improves body sealing and eliminates some openings, particularly at the cowl.

Structural rigidity is enhanced by increased use of 780-MPa (113-ksi) ultra-high-strength steel, which is 27% of the body's steel total. Additionally, door construction was changed from a three-piece assembly to a two-piece by integrating the outer skin with the sash and pressing it together with a stiffener panel, which also improves sealing and saves weight.

The front of the Fit has a custom version of Honda's ACE (Advanced Compatibility Engineering) body construction. Honda has used ACE to enable each new model to get a five-star safety rating from the U.S. NHTSA (National Highway Traffic Safety Administration) and a Top Safety Pick from IIHS (Insurance Institute for Highway Safety), which includes its narrow offset barrier test. And Honda said it will get the same ratings for the Fit.

The Fit, a subcompact with a curb mass range of 2530 to 2642 lb (1148 to 1198 kg), has been a packaging powerhouse since its introduction in 2001 (U.S. market for 2007 model year). The latest iteration, although 1.6 in (41 mm) shorter overall at 160 in (4064 mm), has a larger interior and most significant, a 4.8-in (122-mm) increase in rear-seat legroom to 39.3 in (998 mm). Those numbers surpass those of the Nissan Versa, the previous leader at 37 in (940 mm), which also is comparable to those of an average midsize car, Honda claims. The Versa, at 175.4 in (4455 mm), is a much larger car than Fit, but is an econocar class competitor.

Rear axle revised for legroom

The rear legroom improvement started with a change in the H-shaped torsion beam rear suspension, in which the trailing arms were shortened, which permitted moving the rear axle to the rear. So the rear seat could be moved back too, increasing legroom.

Front-seat legroom remains a competitive 41.4 in (1051 mm), just 0.4 in (10 mm) less than Versa. The inverted U of the torsion beam is now a double-wall design, which strengthens it sufficiently to permit Honda to eliminate the stabilizer bar. Front suspension is MacPherson strut, but redesigned with a hollow stabilizer bar and new geometry.

The extra rear legroom had to come from somewhere, and the answer is that the rear cargo area is smaller. But the Fit's flexible rear seat arrangement permits the rear seats to fold flat, so although the total storage capacity is slightly less, at 52.7 ft³ (1492 L), it's still class-leading. With the seats down, the Fit can hold 10 carry-on bags or 527 rolls of paper towels, the latter good to know in case there's a sale on them at a warehouse club.

One feature that has helped packaging is the center underbody location of the fuel tank, which fits into a recess in the pan and is protected by an underbody cover. The tank has a low-profile shape, which actually was "flattened" slightly from the previous Fit.

Econocars may not have all the electronic bells and whistles, but some are a price of entry. The Fit's rear-view camera is standard. There's an optional 7-in touch screen for the center stack, with a satellite-linked navigation system. If an occupant's smartphone has the Apple Siri "personal assistant," it can be accessed by the Fit if the phone is linked.

"Lane watch," the camera system that provides a video of the area to the right of the car (such as the right lane), was adapted from the Accord. Hill start assist was added, and the electronic stability system is integrated with what Honda calls "motion-adaptive" electric power steering. To correct oversteer or understeer, the system creates a steering input torque that induces the driver to turn the wheel in the right direction. And push-button start is installed on upper trim levels.

The U.S. model is made at Honda's new plant in New Celaya, Mexico, along with production for the Canadian and Mexican markets.

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