Auto Start/Stop - Not a big fan... - PeachParts Mercedes-Benz Forum

Diseasel300 · #1 11-13-2017, 09:35 PM

I'm currently traveling for work and have my first rent-car with auto start/stop. I can't say I'm a fan of the concept.

The first time it did it, I thought the car died at the intersection! Then I noticed the "Auto Stop" on the tach and rolled my eyes. After I realized what it was doing, I decided to give it the benefit of the doubt. It does concern me at night with the lights and everything on wondering if the engine will restart if the battery runs low, or if the battery is getting iffy.

The most annoying part though was this morning. Was freezing and raining outside and when the engine auto-stops, it shuts off the heat!!! That is NOT a feature I wanted when it's cold and I'm trying to commute to the job site! I wound up pumping the brake a couple times just so the engine would stay on and blow some warmth, kind of defeating the purpose.

I do have to wonder about the ecological soundness of starting/stopping the engine at lights. I realize the idea is to try to save emissions, but when the catalytic converter cools down, it is working less efficiently, and the ECU has to richen up the mixture at start, so that's largely defeating the purpose, but more importantly a little 4 banger idling for a minute or so barely uses any fuel anyway, so is it REALLY doing that much or is it a wash in the grand scheme of things?

Just late night ramblings from being bored... I don't think I've ever posted a thread in this subforum.

Angel · #2 11-13-2017, 10:32 PM

if not to save emissions, then its probably to save fuel. Any .1 mpg they can get on the EPA test cycle is potentially worth a lot of money when the us.gov is regulating your corporate average fuel economy.

and I agree - its easy for a new car, with a decent battery and good spark plugs to start-stop in an instant. (stories abound of ECUs that use the alternator as a brake to stop the crankshaft in just the right place, so it can spin and fire quickly on a restart...)
However, once the plugs and wires get flakey, or the battery reaches its last legs...is the ECU gonna know this and turn off the system, or just strand someone in an intersection ?

-John

tbomachines · #3 11-13-2017, 10:43 PM

Some are much better than others. I had a bmw with auto stop and I couldn't stand it. You also had to shut it off every time you got in the car. Good thing that was a loaner.

I recently had a brand new fusion hybrid and I was really impressed with it. The hybrid drive kept everything going and there was absolutely no delay while driving. The engine would come in and out while on the highway buy it was nearly imperceptible.

Diseasel300 · #4 11-14-2017, 07:46 AM

This car is a 2017 Cruze. There's nothing hybrid about it, it's a gasoline-only car. If it were a hybrid, the start/stop would make perfect sense, but since it isn't it really doesn't!

Not completely sold on the automatic dual-clutch manual transmission either. The concept is good - you get the fuel economy and performance of a manual with the ease of operation of an automatic.

Unfortunately it comes with the drawbacks of feeling like being driven around by a 15 year old student driver learning to drive stick, and an appalling shuddering sensation at certain throttle positions, and I swear one of the clutches is slipping already - when accelerating HARD (like to pass someone), the engine makes a weird surging and the car bucks. For a car with 6K on the clock, that's not a promising start in my book.

Zulfiqar · #5 11-14-2017, 03:15 PM

The start stop is a very easy feature to actually work out, the engine always stops in a few same positions. (google GM fast start to see how an old EFI GM engine can start before one round of the starter)

and the best "feature - lol" I have seen to date is the starter died on a jeep grand cherokee. The car auto stopped at an intersection, but failed to start

Diseasel300 · #6 11-15-2017, 11:01 AM

Returned the car yesterday evening and topped off the tank. 129 miles on 3.59 gallons of fuel. That's 35.93mpg with 95% interstate driving. Completely unremarkable economy when you consider the auto start/stop, the fancy automated-manual transmission, electric power steering, and all the other fuel-saving business on that car. My Accord will get economy within 1% of that in the same driving conditions and it's twice the size, 7 years older, has a traditional automatic transmission (the most unreliable one Honda ever made), has no eco-madness (last year they did with no variable cylinder), and has way more power.

For comparison, the SDL did 29.4mpg on a recent highway trip. That was at 75mph with the A/C on. THAT is actually pretty impressive considering it's a 31 year old barge and has no fancy economy improving features at all.

I'm sure there's ways to get higher economy out of the car I was driving if you live with it and learn to use its quirks, but that isn't the point. If the fuel saving features are actually worthwhile, they'll save fuel and cut emissions with ANYONE at the wheel, and without that irritating start/stop business. When it's below freezing and raining, I want my heat!!!

tjts1 · #7 11-15-2017, 11:09 AM

Quote:

Originally Posted by Diseasel300

This car is a 2017 Cruze.

Rents a ****box, complains about ****box technology. Extrapolates that all technology must be ****.

Diseasel300 · #8 11-15-2017, 11:24 AM

Quote:

Originally Posted by tjts1

Rents a ****box, complains about ****box technology. Extrapolates that all technology must be ****.

That is an incorrect summation. I'm using a single point of reference for a new technology. Having never driven a car with auto start/stop, it was a new thing to me. Not one I like or appreciate.

The previous ****box that the Cruze replaces - the Cobalt - will get similar economy if driven carefully. Still a piece of ****, but the point remains valid - all that extra complication for what? Tax credits? Feeling good?

engatwork · #9 11-15-2017, 03:29 PM

The wife's GLK has it and I don't like it at all. I would have rather seen it designed where you have the turn it on if you want it, not where it is turned on whenever the vehicle is started.

tbomachines · #10 11-15-2017, 08:38 PM

Quote:

Originally Posted by Diseasel300

Returned the car yesterday evening and topped off the tank. 129 miles on 3.59 gallons of fuel. That's 35.93mpg with 95% interstate driving. Completely unremarkable economy when you consider the auto start/stop, the fancy automated-manual transmission, electric power steering, and all the other fuel-saving business on that car. My Accord will get economy within 1% of that in the same driving conditions and it's twice the size, 7 years older, has a traditional automatic transmission (the most unreliable one Honda ever made), has no eco-madness (last year they did with no variable cylinder), and has way more power.

For comparison, the SDL did 29.4mpg on a recent highway trip. That was at 75mph with the A/C on. THAT is actually pretty impressive considering it's a 31 year old barge and has no fancy economy improving features at all.

I'm sure there's ways to get higher economy out of the car I was driving if you live with it and learn to use its quirks, but that isn't the point. If the fuel saving features are actually worthwhile, they'll save fuel and cut emissions with ANYONE at the wheel, and without that irritating start/stop business. When it's below freezing and raining, I want my heat!!!

Well, I'm just going to leave this here.
https://www.fueleconomy.gov/feg/Find.do?action=sbs&id=37907&id=29660

Not quite 1%...and if you want to compare diesels, take a look at the cruze diesel.

tjts1 · #11 11-15-2017, 08:39 PM

Proper start/stop systems use ultracapacitors to store enery for each restart. Lead acid battery will have a short life in this type of usage.

Diseasel300 · #12 11-15-2017, 08:52 PM

Quote:

Originally Posted by tbomachines

Well, I'm just going to leave this here.
https://www.fueleconomy.gov/feg/Find.do?action=sbs&id=37907&id=29660

Not quite 1%...and if you want to compare diesels, take a look at the cruze diesel.

Except I have the 4-banger, not the 3.5L V6 in your link. It routinely returns 34-35mpg on the highway, upper 30s with ethanol-free gas.

Modern diesels are so much more fuel efficient than anything else out there, but the emissions systems are their achilles' heel. Like everything else, that should evolve over time into a more durable system too. Bad press like the VW emissions-defeat scandal certainly doesn't help their market either.

tbomachines · #13 11-15-2017, 09:01 PM

Quote:

Originally Posted by Diseasel300

Except I have the 4-banger, not the 3.5L V6 in your link. It routinely returns 34-35mpg on the highway, upper 30s with ethanol-free gas.

Modern diesels are so much more fuel efficient than anything else out there, but the emissions systems are their achilles' heel. Like everything else, that should evolve over time into a more durable system too. Bad press like the VW emissions-defeat scandal certainly doesn't help their market either.

Sorry, assumed that based on your reference to cyl deactivation which was only v6s.

I imagine that if you are returning higher mpgs than rated (31) on the 4cyl you'd probably be able to easily strike over 40 in the cruze with a bigger sample and getting a chance to drive it farther than 150 miles. Fwiw the fusion I referenced in my first post hit 49.6 (so close!) Over 500 miles. Start stop obviously doesn't have any effect on highway mileage.

Diseasel300 · #14 11-15-2017, 09:29 PM

The newer Hondas will run 2/4 cylinder modes depending on load, they also now have CVT's. The v6's got the cylinder deactivation with the 2008 model refresh. The 4 bangers came later on.

When I had my 5 speed Civic, I often skipped gears and coasted a lot. I never got less than 34mpg in city driving. On the highway, it usually did 42-44. Was a great commuter car during the gas crisis ~10 years ago!

davidmash · #15 11-16-2017, 12:54 AM

Quote:

Originally Posted by Diseasel300

Returned the car yesterday evening and topped off the tank. 129 miles on 3.59 gallons of fuel. That's 35.93mpg with 95% interstate driving. Completely unremarkable economy when you consider the auto start/stop, the fancy automated-manual transmission, electric power steering, and all the other fuel-saving business on that car. My Accord will get economy within 1% of that in the same driving conditions and it's twice the size, 7 years older, has a traditional automatic transmission (the most unreliable one Honda ever made), has no eco-madness (last year they did with no variable cylinder), and has way more power.

For comparison, the SDL did 29.4mpg on a recent highway trip. That was at 75mph with the A/C on. THAT is actually pretty impressive considering it's a 31 year old barge and has no fancy economy improving features at all.

I'm sure there's ways to get higher economy out of the car I was driving if you live with it and learn to use its quirks, but that isn't the point. If the fuel saving features are actually worthwhile, they'll save fuel and cut emissions with ANYONE at the wheel, and without that irritating start/stop business. When it's below freezing and raining, I want my heat!!!

To be fair, the auto stop is for stop and go traffic, not interstate so I am not surprised that your interstate driving MPG is not remarkable. My guess is that if the driving were 95% city I think the results would be different.