Longer, lower, wider, more aero, and stylish Corolla unveiled

  • 10-Jun-2013 05:07 EDT
aei-corolla display.jpg

The Corolla's styling gets an upgrade to go along with better aerodynamics, standard LED low beam headlamps, and a CVT that provides conventional transmission shift feel.

Longer, lower, wider, and sleeker, with a 0.28 Cd body, might be what you’d expect in the new model of a lot of cars but hardly the Toyota Corolla, the reliable A-to-B transport since introduction 47 years ago. Just as unlikely are a stiff new body, a rear suspension modified for handling, and an engine with both variable intake-valve timing and lift. The 2014 model, on sale this fall, was unwrapped for a "reveal" (quick look) late last week, and many details were unexpected.

Although the 2014 Corolla, an 11th generation model, isn’t a technological test bed, it has innovation for its market category, including a mechanical CVT (continuously variable transmission) with improved efficiency and a ratio change strategy that should make it palatable to drivers who reject a CVT's “rubber band” feel.

A four-speed automatic and six-speed manual will continue to be offered, but the CVT is expected to have an 80% take rate. Many CVTs offer a “manual” mode with simulated shifts. The new Corolla S-Grade (sportiest of the four trim levels: L, LE, LE-Eco, and S) will have a seven-ratio version in the Sport lever position. And in Drive mode, it will feel as if it’s going through stepped gears, Toyota said. However, the Corolla still is an economy car, and one obvious reason for that CVT is fuel economy, which Toyota said will be “over 40 mpg” for the LE-Eco model.

The transmission is Toyota’s own design, explained Chief Engineer Shinichi Yasui, and incorporates a number of high-efficiency features. It is not based on the one used by Toyota-affiliate Subaru, he insisted.

CVT has 6.3 ratio spread

He said the CVT is a steel link belt type. With internal-housing engineering to maximize the size difference between the pulleys, Toyota has been able to get a 6.3 ratio spread—a range of 0.396:1 to 2.48:1—transferred to a 4.761:1 final drive.

Because the new model was on a strict weight-maintenance program—"under 2900 lb" or 1315 kg for all models was the stated objective—the size of the CVT was constrained. Clearly it could have a greater ratio spread if desired by simply making the transmission housing larger to accommodate larger pulleys. But 6.3 is at the top of class for current ratio spreads and the "over 40 mpg" promise is about 20% higher than the 34 mpg highway rating for the 2013 model. Toyota said that the pulley sizes it is using and the clearances within the housing are an "optimized" package but at this time would provide no further detail.

Several steps were taken to reduce parasitic losses, including use of low-viscosity fluid and fluid warmer. Furthermore, the typical CVT, with a pump drive proportional to engine speed, is developing more pressure at high rpm than needed for lubrication and peak clamping pressures of the split pulley halves. So, Toyota said its CVT oil pump is driven through a co-axial port system that permits a 25% reduction in peak pump drive torque.

This CVT will not be used on Camry, Yasui said, but is projected for installation in the Yaris and other Corolla and smaller models. It has a torque converter, he added, intended only to smooth initial engagement, as it locks up at very low speed.

The CVT Sport mode on the S-Grade and Eco mode for the LE-Eco both recalibrate accelerator response (less for Eco, more for S-Grade) and change ratios (more economical for Eco, more aggressive for S-Grade) if left in Drive. The driver can move the S-Grade shift lever to the manual S position and use the lever or steering wheel paddle shifters to go through seven fixed ratios. The S-Grade also is available with the six-speed manual, which is the base transmission on the L.

Valvematic boosts fuel economy 5%

The four-cylinder engine displacement remains at 1.8 L but will be offered in two versions. One is a carryover with variable intake and exhaust valve timing, rated at 132 hp (98 kW) and 128 lb·ft (174 N·m). The other—for LE-Eco only at this time—has a higher compression ratio (up from 10:1 to 10.6:1) and infinitely variable intake-valve (only) lift and timing, called Valvematic. This electrohydraulically actuated system has been used in some Japanese market engines since 2007.

Valvematic can eliminate the throttle, using changes in lift and timing to control air intake and therefore engine rpm. On the 1.8-L, it increases power to 140 hp (104 kW). Although there's a slight loss in torque vs. the carryover 1.8 L to 126 lb·ft (171 N·m), peak torque on the new engine comes in at lower rpm (4000 vs. 4400 for the carryover). More important to Toyota, the Valvematic system alone improves fuel economy 5%, Yasui said. Both engines retain port fuel injection.

The Corolla will be made in Blue Spring, MS, and Cambridge, ON, Canada, plants with North American content approaching 90%. However, the CVT will be brought in from Japan, as it requires a specific assembly line already built for the Japanese market, noted Andrew Coetzee, VP of U.S. Product Planning.

The new Corolla is 182.6 in (4638 mm) long overall, a 3.90 in (99 mm) increase, on a 106.3-in (2700-mm) wheelbase, which is 3.93 in (100 mm) longer than the 2013 model. Overall width is 69.9 in (1775 mm), an increase of 0.63 in (16 mm). Height is 57.3 in (1455 mm), 0.39 in (10 mm) lower.

The smaller 2013 model with automatic transmission had a mass of 2800 lb (1270 kg), but the increase in size and stiffening of the 2014 body was offset by greater use of high-strength steel. Toyota said the new body with its floorpan bracing is far more rigid than its predecessor. Corolla spring rates were selected for a relatively soft ride, with one exception: the S-Grade has specific springs, shocks, and bushings, and 17-in wheels (vs.15- and 16-in for other models) for improved handling.

Overall, the Corolla continues with MacPherson struts in front, although the control arm is more rigid. The rear retains the torsion beam, but its bushing mounts to the body are diagonal to improve rear-end grip and stability in aggressive cornering. Toyota believes that, with the stiffer body and suspension revisions, all Corollas should handle noticeably better.

Comparatively tame styling of the previous Corolla notwithstanding, it was a relatively aerodynamic vehicle, with a Cd of 0.29, so doing better than the 2013 was likely not easy. The aggressive styling of the 2014 model is not in itself necessarily more aerodynamic, but a layout of underbody covers on the LE-Eco smooths airflow to help lower the number to 0.28.

Cloth is the base seating material, but SofTex synthetic leather (see http://www.sae.org/mags/aei/11983) is an option. LED low beams are standard on all trim levels.

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