MINNEAPOLIS – Kia first planned to introduce stop/start technology on its refreshed '12 Soul model two years ago.
But after driving preproduction models with the technology, car reviewers took issue with the violent shudder caused by the engine restarting.
Kia pulled back on stop/start for '12, although it quietly reintroduced the feature for '13.
Now, the automaker says it has tinkered with the technology further for the second-generation '14 Soul, on sale this month at U.S. Kia dealers.
"It's much more smooth than before," Orth Hedrick, director-product planning for Kia Motors America, says here on the sidelines of a ’14 Soul media preview.
Nayan Engineer, an engineer with Hyundai/Kia's Superior Township, MI, technical center, tells WardsAuto R&D solved the previous stop/start-equipped Soul's noise, vibration and harshness issues with several design improvements.
Among them, Kia switched to a bidirectional crank-position sensor, which it says is more precise than the conventional sensor on the ’13 model. It also modified the starter to lessen noise and shock, and further smoothed out the operation by reprogramming the engine controller.
Kia says to expect Souls with stop/start, which it calls Idle Stop & Go or ISG, to achieve 1 mpg (0.4 km/L) better fuel economy in city driving, or 24/31 mpg (9.8/7.6 L/100 km) city/highway on the Soul+ grade with the technology. Souls without ISG but the same engine are expected to average 23/31 mpg (9.9/7.6 L/100 km) city/highway.
It had been unclear if gains from the technology would show up in fuel-economy figures, as some in the industry wondered whether the U.S. EPA's city test cycle would reflect the fuel savings possible with stop/start.
ISG is paired with Kia's 164-hp 2.0L 4-cyl. in the Soul+, not the Base grade's 1.6L 4-cyl., as had been the case in '12. The 2.0L Soul+ comes standard with a 6-speed automatic transmission.
Idle Stop & Go is part of the Soul+ grade's $400 Eco package.
While $400 is more than other automakers charge for a stand-alone stop/start system (Ford lists the feature at $275 on the Fusion midsize sedan), Kia is adding extras that justify its higher price point, Hedrick says.
Low-rolling resistance tires fitted around 16-in. alloy wheels and improved aerodynamics, thanks to full underbody panels, also are part of the Eco package.
While buyers selecting the green-focused package still get most of the features standard on the Soul+, including cruise control and a rear center armrest with cupholders, its addition impedes most add-ons.
For instance, the car's panoramic sunroof, optional 8-in. (20-cm) touchscreen, navigation system and heated front and rear outboard seats, cannot be had on models with the stop/start system.
Stop/start can be fickle.
Kia officials note conditions must be just right for the technology to function as designed.
Air-conditioning set for maximum coolness on hot days likely would preclude the engine from shutting down, as the compressor needs to run to maintain the specified chilly interior temperature.
A long stoplight also could result in the engine running periodically, as emissions-cleansing is best accomplished when the engine and catalytic converter are hot.
Stop/start has been standard on hybrids for years as a means of improving city fuel economy.
Pairing it with non-hybrid powertrains is a relatively new idea in the U.S., and one few automakers have adopted, even in light of stronger U.S. government emissions regulations.
Other than Kia and Ford, General Motors is the only mass-market manufacturer to have stop/start. It is standard technology in the '14 Chevrolet Malibu midsize sedan with a 2.5L 4-cyl. engine.
Even the Volkswagen brand, which uses stop/start extensively throughout its European lineup, doesn't yet offer it in the U.S., other than in the Jetta Hybrid.
Kia's sister brand Hyundai hasn't pulled the trigger on stop/start for non-hybrids in the U.S., nor have Japanese automakers Honda, Nissan and Toyota.
Where stop/start flourishes in the States is in the premium segment, at least among European manufacturers. The feature has been standard or optional on vehicles in Europe for years.
Audi's A4, A8, Q5 and Q7 models have stop/start, as do BMW's 3-Series, 5-Series and X5.
Porsche has stop/start on the Panamera and Cayenne models, while Mercedes-Benz just introduced it as standard on the '14 E250 diesel.