Car Tech 101: Auto-start-stop explained
5:47

Car Tech 101: Auto-start-stop explained

Auto Tech
[NOISE] [MUSIC] Auto start stop, or auto stop start, whatever you want to call it, call it mainstream. Something like two thirds of all cars in the EU have it. Had it for a long time. Every BMW I've driven in the last three years has had it. Ford says they're gonna have it on two-thirds of their F-150s, 70% of their entire fleet by the 2017 model year. I can go on and on. It is here to stay. But what is it? And how does it work? [MUSIC] The technology's been around since. Toyota first offered it on a Crown sedan in the mid 70s. VW put it into mass production in the early 80s on a version of the Polo. Now auto start stop has come later to the US for a variety of reasons. Reasons. Primarily, the fact that we have much less sensitivity to fuel the economy. Because we traditionally had much lower fuel prices relative to average household income. That's well known. We also have less sensitivity to emissions, at least historically, in this country. Which is also related to running an engine less than you have to. But in general the world is becoming And the auto start stop when I'm on the [UNKNOWN]. [MUSIC] Now the name should tell you everything, but let's see very clear. Here's what it does, I come to stop in traffic and the electronics that run the engine stopped the engine. They do that [MUSIC] [INAUDIBLE] And just the engine by the way. By turning off the spark to the ignition, and turning off the fuel flow to the cylinders. Then when I lift off the brake, those are instantly restored, and the engine is restarted by its starter motor, to. hopefully instantly come back to life, now ideally that transition from off to on to off to on takes place in just an instant almost imperceptively, but allowing a car to do that requires much more than you can do You just twisting a key. [SOUND] First, this is engine shutdown, not car shutdown. The electronics stay on and they don't hiccup or flicker when the engine restarts. Next, the car should have electric assists and pumps, not belt-driven ones. So you don't loose things like power steering or automatic transmission readiness when the engine's down. You need a tougher starter motor because it's gonna be doing its job a lot more often. A deep cycle battery, which is one designed to be deeply discharged and then recharged readily Sometimes a car will even have a second battery for auto start stop, an air conditioning system that can override auto stop sometimes to maintain cabin temperature, and harder, smoother internal engine friction surfaces for durability. Starting is hard on engine bearings. [MUSIC] Now if you're driving a hybrid car, there's a little bit of a difference there in that you already have a large battery, the big motor battery that can handle the start-stop electricity, and you've got an integrated motor in the power train that can also function as a starter, not using a traditional starter like a standard gas engine car would do. And, by the way, auto start-stops are available on manuals or automatic. Most cars are automatic, so It's really what we care about. [MUSIC] You can save anywhere from 3 to 10% of the fuel you would otherwise use without start-stop by having the technology. Those numbers are huge in the automaker world where they will spend Millions to gain 1% more fuel economy. The downside is you can't take those numbers to the bank. It varies wildly depending on the kind of routes you drive. If you live in Montana, where everything is a two hour interstate Drive and everything else, you may see very little if any benefit from auto start-stop. If you live in Los Angeles, you may very quickly get auto start-stop to pay for your Xanax prescription that you take because of your commute. It varies very much by how and where you drive. Okay, after driving almost every car out there with with auto stop-start, let me give you my shopper's tips for what to look for in a car that has it. Fast restart with the goal being the time it takes to move Move your foot from the brake to the gas. Very few cars get it done that quickly. Most do not. Few rotations, slightly different. This is the number of engine rotations taken within that restart window to get the engine running again. I find this varies as well. The low body vibration, related to the number of rotations, as well as the engine mount technology. I don't want my German luxury car to feel like I"m starting a 72 Bronco every time I lift off the brake. And it should be defeatable, of course. Most cars have a button for this. A few do not. [MUSIC] Now that's it, shopping for auto start stop isn't necessarily all in your hand. Know that whether you like it or not, it's here to stay because carmakers like it. More than that, they need it. Because it's incorporated in the results they get, in the EPA mileage test cycle. It can do wonders for their fleet fuel economy. So, they're not going to get rid of it just because a few owners say, eh, I dont like it or I keep defeating it. Okay, so the bottom line penciling out the value of auto start stop to you, in your pocket book. So let's ballpark that it costs $250 to $300 worth of the MSRP of a car you buy that has it. Now earning that back is the complicated math it depends on fuel prices Is in your area, how many trips you take each week, and what kind of trips are they. And whether you have propensity to defeat auto start stop some of the time, none of the time, or worst of all, all the time. In which case it's never gonna pay for itself. [MUSIC] More car tech demystified right now at CNETOnCars.com. Click on Car Tech 101. [MUSIC]

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