Gadgetory

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 we're gonna have it on two thirds of their f150 seventy percent 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 the technology has been around since Twila 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 u.s. for a variety of reasons primarily the fact that we have much less sensitivity to fuel economy because you 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 an auto start-stop automotive commuters now the name should tell you everything but let's be very clear here's what it does I come to a stop in traffic and the electronics that run the engine stop the engine they do that adjust the engine by the way by turning off the spark to the ignition and turning off the fuel flow to the cylinder then when I lift off the brake those are instantly restored and the engine is restarted by its starter motor to so they instantly come back to life now ideally that transition from off to on off to on takes place in just an instant almost imperceptibly but allowing a car to do that requires much more than you can do just twisting a key first this is engine shutdown not car shutdown the electronic 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 lose things like power steering or automatic transmission readiness when the engines down you need a tougher starter motor because it's going to 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 the 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 as hard on engine bearing now if you're driving a hybrid car there's a little bit of a difference there and that you already have a large battery the big motive battery that can handle the start/stop electricity and you've got an integrated motor in the powertrain that can also function as a starter not using a traditional starter like a standard gas engine car with you and by the way auto start stops available on manuals as well as automatics though most cars are automatic so it's really what we care about you can save anywhere from three to ten percent of the fuel you would otherwise use without start/stop by having the technology those numbers are huge in the auto maker world but they will spend millions to gain one percent for a 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 you live in Montana where everything is a 2-hour interstate drive from 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 community it varies very much by how and where you drive okay after driving almost every car out there with auto start-stop let me give you my shoppers tips for what to look for in a car that happened fast restart with the goal being the time it takes to 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 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 if you do not now that said shopping for auto start-stop isn't necessarily all in your hands know that whether you like it or not it's here to stay because car maker is like more than that they need it because it's incorporated in the results they get in the epa mileage test cycle and can do wonders for their fleet fuel economy so they're not gonna get rid of it just because a few owners say I don't like it or I keep defeating okay so the bottom-line penciling out the value of auto start-stop to you in your pocketbook let's ballpark that it cost two hundred and fifty to three hundred dollars worth of the MSRP of a car you buy that has it now earn that back is the complicated man it depends on fuel prices in your area how many trips you take each week and what kind of trips are they and whether you have a propensity to get the 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 more car tech demystified right now at CNET on cars comm click on car tech 101