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Stupid useless Eco Stop/Start "feature" in newer cars!

in addition to a beefed up starter, these cars also need electric AC, electric power brakes, and electric power steering, for obvious reasons. Which is a lot for the tiny MPG boost.

Which, to me, is good, as the electric subsystems should be more reliable than the vacuum/hydraulic systems. Although I don’t know of any purely electric brakes, so they would need an electric driven hydraulic pump.

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Funny, we used to get along just fine without power steering, power brakes, and AC. A lot of cars already use electric power steering. I’m sure electric AC and brake assist will come soon if it’s not already here. Well, it IS already here, how does a Tesla roadster power its brakes and AC?
As for a “tiny” mpg boost:

  1. Don’t underestimate the idle fuel consumption of a gasoline engine. For a high performance V-8, it’s something on the order of .4 to .6 gallons per hour.
  2. Don’t underestimate the amount of time a typical car spends idling at a stop light. In the last 180 miles I drove, my gps trip computer recorded 48 minutes of stopped time.

If a car alternator can be hacked into a go-kart motor with performance comparable to that of a lawn mower powered go-kart, I’m sure that an alternator could be configured to start the engine as well as charge the battery.

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That is a very good point for new car shoppers, but in this case the car in question was a used car, so I think it is safe to assume that either the OP failed to test drive his chosen vehicle, or he wasn’t annoyed by that feature during the test drive.

the 2015 S550 has a turbo 4.7L motor which seems different spec wise than the 2018 S550 which uses a turbo 4.0 motor. the 18’ model might have the combo alt/start device but i do not think the 15’ does?

I’ve always driven the car I wanted to buy before I bought it. It seems that every car on the lot is a demo around here. The ones I’d stay away from are the loaners given to people that leave their car for repairs or maintenance. Those cars should be sold as used cars when they are sold.

The starter Mercedes uses for this feature isn’t a normal starter. It’s made to withstand repeated use.

I don’t consider the amount of fuel saved over time minuscule, but I suppose since you can afford a Mercedes, you’re willing to waste money spent on fuel. Even if I had that much disposable income, I’d care about air quality and reducing pollution.

The first time I drove a Prius this feature took about five minutes to get used to. Talk about first world problems…


yes, the prius joy stick shifter takes a bit to get used to. it is vertical and spring loaded. you push it forward into drive and than release it and it snaps back to vertical and you are in drive, even though shifter does not stay in the drive position. almost everyone is perplexed by this shifter. while you are moving you can pull shifter back to the B position and the system will use regenerative braking while you hold shifter and you foot is off gas pedal. light application of brake pedal is also regen braking. hard brake pedal is regen and mechanical brakes combined

Like horsepower figures and weight loss figures MPG figures are quite inflated. No doubt a 5 liter engine can produce 1,000 horsepower long enough to run 440 yards in a matter of seconds and 6 months of 15 minutes per day on the Total Gym can result in weighing 100 pounds less I wouldn’t bet my house and the stuffing in my mattress that I would have those results. From the beginning I have felt somewhat sure that dollar for dollar buying and driving a Corolla would be preferable to a Prius for the vast majority of us.

And the Stop/Start feature might eventually be considered on a par with the Cadillac 4-6-8 system for its technological genius.

you stop at light. after 3-5 secs the motor shuts off? do you have to touch gas pedal to start motor? i live near very annoying stoplight. it is timed for cross traffic and opposing flow traffic. i usually wait 2+ minutes for green light. its 4 blocks from my house so car is always cold in morning. sitting at light for 2+ minutes with cold motor when its -5F kinda sucks

Thanks for the details. Do they apply for cars before 2018, like the 2015 for the OP?

europe only! not the OP’s 2015 S550. story does not say if THIS fancy motor has eco-start also?

The biggest news in the S-Class engine world isn’t news at all for the United States. A new S500 model is being launched in Europe and elsewhere in the world, powered by an all-new M256 engine sporting a cutting edge 48-volt electrical system that allows it to combine mild hybrid functions with starter-generator functions through a sandwiched electrical drive unit. This, in turn, allows Mercedes to convert all of the external accessories from their archaic belt-drive to more efficient, and more controllable, electric-driven accessories. Getting rid of the accessories on the front of the engine also decreases its length, making it easier to package the M256’s inline six-cylinder layout. Electric-drive accessories on the M256 include the engine’s water pump and the air conditioning compressor, but also an electric supercharger that fills the 3.0-liter inline six-cylinder’s torque gaps. The result? A more efficient, smarter engine that’s capable of 429 hp and 383 lb-ft of torque in S500 trim. Those figures net the M256-powered S500 a 0 to 60 mph time of roughly 4.7 seconds. Unfortunately, we won’t get this powertrain in America — or at least there are no plans for it as yet.

On most cars the system keeps the engine running during warmup and times of high electrical load.

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I think it all depends on the CAFE standard and how much time is spent at idle during that test (if any). I have no idea… But must be a significant part or the industry would never have adapted the stop/start feature.

Actually,I did NOT have a test drive because the car was used, and being shipped from another Mercedes dealer a few states away. I was trading in the same model, only eight years older, so I was confident the drive experience would be the same or better. It is better, and I love the car, except for this one folly. And no, I still don’t give a crap about the gas mileage. I don’t drive enough to worry about it.

Without paying one red cent, you can test drive a Prius and experience what it’s like. It’s not nearly as annoying as you might think once you’re used to it. There is no delay in the throttle response.

We also used to “get along” with outhouses and a lack of central heating, but I doubt if most people would think that we should return to the “good old days” in regard to the lack of those creature comforts. Similarly, I doubt if people would like to forego PS, PB, and AC. In fact, because of disc brakes, I don’t think that it would even be possible to forego power assist for braking.


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My motorcycle has non power assist disc brakes and I don’t need Popeye arms to lock up the front wheel. I would say that non power assist disc brakes in a small car is indeed possible.
I once did an experiment with my Toyota Yaris. I switched off the engine while coasting and used the brakes repeatedly until the vacuum was used up. I had to push harder on the pedal, but I was still able to stop the car.

Not to argue but power steering, brakes, and air conditioning were always add on options at additional cost. When they became more popular and justified to make them standard production packages they were added. So I would have no problem with the start-stop feature being an add on option. Then when it became popular it could be part of the package. Unfortunately the reason for it is EPA regulations again and not customer demand. I gotta question how many people would actually pay extra for this feature and likely only big city dwellers? I wonder if its included in the police package?

When my father taught be how to drive in 1989 in a 1969 Dodge Dart, I expressed reticence regarding the manual (non power) brakes. My father showed me how easy it was to lock them up without power assist. In truth, when you press a manual brake pedal in that car, your forward momentum became the “power assist.”

Yes, but did that '69 Dart have disc brakes?