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Stop/start to be standard with V-6 in Jeep Cherokee and I-4 in 2015 Chrysler 200; up to 3% better fuel economy

Chrysler Group is offering fuel-saving Engine Stop-Start (ESS) technology as standard equipment on certain models of the award-winning 2015 Jeep Cherokee mid-size SUV and 2015 Chrysler 200 mid-size sedan.

Chrysler 200 customers who opt for the 2.4-liter Tigershark I-4, and Jeep Cherokee customers who choose the available 3.2-liter Pentastar V-6, will experience estimated fuel-economy improvements of up to 3%, compared with the conventional vehicle-engine pairings. ESS applications in the Chrysler 200 and Jeep Cherokee will also account for an estimated CO2 emissions-reduction of up to 3%.

Availability in the popular Jeep Cherokee is scheduled for third quarter. ESS arrives the following quarter in the all-new Chrysler 200.

The technology made its NAFTA-region debut in the Ram 1500 full-size pickup. ESS accounts for a one-mpg city-cycle fuel-economy gain in the Ram, the most fuel-efficient truck in its segment.

At the heart of ESS is a high-speed/high-durability starter that reduces crank time, culminating in quicker restarts. Its function is regulated by algorithms that act on a vehicle’s powertrain and chassis components.

As a result, acceleration is aligned with driver inputs. Passive accelerator application is met with measured throttle response; hard inputs trigger aggressive starts.

Engine controls constantly monitor vehicle speed. When the vehicle brakes to a stop, fuel flow is cut and engine turns off; batteries maintain other vehicle systems so in-cabin comfort is unaffected

When the brake pedal is released, the engine automatically restarts and the nine-speed automatic transmission is engaged within 0.3 seconds

If a driver chooses to forgo the benefits of ESS, the feature can be deactivated with the push of a button, and then reactivated.

The 16-valve, 184-hp 2.4-liter Tigershark comes standard in the all-new 2015 Chrysler 200. The I-4 also features the MultiAir2 electro-hydraulic fully variable valve-lift system.

Exclusive to Chrysler Group in North America, MultiAir technology uses a column of oil in place of the traditional mechanical link between the camshaft and intake valves. Electronic control of the MultiAir components maximizes intake manifold pressure, significantly reducing pumping losses.

MultiAir2 simultaneously controls both valve opening and closing events to more effectively manage combustion quality. This ensures the appropriate, effective compression ratio and efficient internal exhaust-gas recirculation (EGR) for improved fuel economy.

The all-new 2015 Chrysler 200 is the first mid-size sedan to feature a nine-speed automatic transmission, which comes standard and contributes to a fuel-economy gain of up to 13% compared with the outgoing car and its four-speed gearbox. The transmission is also standard in the Jeep Cherokee.

The Cherokee’s available 271-hp 3.2-liter Pentastar V-6 is derived from the 3.6-liter Pentastar V-6, named three times one of Ward’s 10 Best Engines. The smaller-displacement V-6 helps the Cherokee deliver fuel-economy improvements of up to 30%, compared with the model it replaces.

Individual exhaust-manifold runners are integrated into the aluminum cylinder-head casting, a key Pentastar-family differentiator. This design feature reduces weight and affords packaging benefits.

The 24-valve engine’s 10.7:1 compression ratio aids in lowering fuel consumption and improves performance while its variable-displacement oil pump further reduces parasitic losses to maximize fuel economy. The pump is programmed to operate as needed, staying in low-pressure mode below 3,500 rpm, and then bumping up pressure as demand follows engine-speed.


Jim McLaughlin

And what voltage does the starter (and presumably the air conditioning) operate at?


All the start/stop mild hybrids of which I have knowledge are still 12v. Some of them operate the batteries at the top of the standard range (14v), and many (like the Malibu) have an additional 12v battery mounted in the rear. But 12v it is.

If you're thinking that's kind of clunky, I agree. An earlier post here talked about Navigant's projection of 48v systems finally becoming widespread. IMO it's definitely about time.


PS the original presser at says "beefier batteries", with beefiness not referenced to voltage.


Generation I BAS
A 36 volt electrical system (operating at 42-45 Volts) is used to operate a permanent magnet motor/generator unit mounted to the engine in a similar fashion to a conventional alternator.

Generation II BAS (eAssist)
While still a Belted Alternator Starter system, the system is named eAssist and includes a larger more powerful Hitachi-supplied[citation needed] 115 Volt Lithium Ion battery and a 15 kW (20 hp) motor-generator that delivers 79 lb·ft (107 N·m) of torque.


SJC, I also thought that Chevy’s eAssist kept the earlier “mild hybrid” configuration. However, in 2014 they realized that they could pretty much achieve fuel efficiency parity with a less expensive 12v system and so quietly changed it (even after delivering a few '14s with the ’13 configuration):

Basically they dropped the modest launch assist that came from the more powerful 2012-13 eAssist. The question becomes: is it just start/stop, or is it a mild hybrid? I confused the terms in my post. I think wherever you see start/stop without launch assist, the power bus is 12v. It doesn’t help that GM seems to have a lot of trouble with name designations and the whole consumer education thing. (The moral outrage of a small fringe of customers over Volt’s transmission direct ICE-to-wheels mode and the implications of non-EVness resonates to this day.)

Now, the system DIDN’T change for the Buick Regal, as I understand it. But the Regal competes in a slightly different segment.

As usual, customers are fed such a variety of naming conventions (especially when branding is added) that you can’t really tell what’s being offered --- imagine how much harder this gets for people who really aren’t literate in the technology.


One of the absolute LAST things I want on any automobile I own is a stop/start system that is not an inherent part of powertrain design.

In other words, if the stop/start system is an "add-on" item, I do not want it. If it is an integral part of the powertrain architecture like an HEV, then no problem.

The thought is this, at idle, an engine burns almost no fuel. My specialty is with diesel engines, and the miniscule fuel consumption savings at idle conditions does not in any way warrant an obnoxious stop/start system. The last thing I want is an intrusive, annoying, expensive system whose only purpose is to satisfy unreasonable CAFE standards.

The only place such a system may make sense is in countries like Greece where gasoline is approximately $10/gallon.


I just put that up as a point of reference. Chevy new is doing start-stop with no e-assist for the Malibu, 2013 was the last year for a Malibu e-assist. 2014 has the start-stop with the second battery in the back.

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