MHEV / belted alternator starter
 

Does anyone have experience test driving one of the new models that include the Mild Hybrid (MHEV) 48v battery system with belted alternator starter (BAS) used for start / stop functionality? This is one of the things I'm anxious to know about for the new A6.

My current vehicle does not have start / stop functionality (the gas engine turns off when you stop at a traffic light). I've rented a few cars over the last few years and I hated the stop / start systems they employed, mostly because of the delay and vibration of restarting the engine. Those were all using the normal pinion starter method.

Audi's advertised this BAS system as no delay, no vibration from the materials I've seen. I've yet to find a test drive type video on YouTube where someone talks about the system and whether is really is as good as Audi says. The test drive videos don't mention it or you get the Audi animation about how the system works.

I have read every review about the A6 and A7 I could find including foreign sources and have not seen anything negative about the start/stop system. Most just mention that it has it and the 48v battery is used for it. Digital Trends said the most about it that I could remember, it says "In this case, electrification takes the form of a mild hybrid system consisting of a belt-alternator and a 48-volt electrical system fed by a lithium-ion battery hidden under the trunk floor. The technology boosts fuel economy while helping fire up the engine faster and more smoothly after the stop-start system turns it off. The hybrid system’s presence is virtually indiscernible in normal driving conditions. It interferes when needed without fundamentally changing how the A6 drives, which is precisely how Audi envisioned it.".

I'm sure once the car is available in the US we will get more detailed reviews and any stuttering, vibrations, etc. will come to light.

I read the same. I also read that the Audi senses the car in front of it moving and starts the electric system at that time. I too have rented start stop cars and they suck. Audi seems to have overcome that concern according to one of the salesman at the dealership who attends all the workshops for the A6... He knows a lot of stuff I have not read anywhere...

BTW, the A6 build is still messed up. The interior colors are wrong as well. Weird they would launch that build and be so far off the mark. Left hand needs to talk to the right one...

a8 review in usa: https://www.engadget.com/2018/10/19/...udi-a8-review/

The other thing to note is that the high speed deactivation of the engine as in Europe (when coasting to a stop) is not an active feature in the A6/7/8. This is taken from the article from the A8 forum that states something along the lines of "4 things the A8 won't have at launch". That's where I learned that bit.

This is disabled, for some reason. Probably some dumb law.

I don't think it is a law, I read in a review it is because the engine didn't start up fast enough for the way US drivers drive on highways.

Based on the Engadget review if it can start so fast and so seamlessly from stop-go, wouldn't this issue not be a problem?

I've seen some Youtube video about this system in a drive POV - AutoNL or something or other. It was pretty darn seamless. But anyways, we can both theorize but we don't know why for sure, but we do know it's disabled for us.

No, I wouldn't think that necessarily means anything since that is from a stop and not while cruising on a highway where the throttle would be filly engaged at any time and the drive is expecting the car to react immediately. I will see if I can find the article.

Good point, that and the transmission has to get up to speed to get synced with the engine.

But yes, if you can find it and you wouldn't mind sharing it, I'd love to have a read.

From the article, it was concerning the A7 but same system: "European models also benefit from a coasting function that shuts off the engine when not needed between 34 and 99 mph to save fuel (0.7 liters per 100 kilometers to be exact), but that system was deemed to restart a tad too slowly when re-engaging the throttle for American tastes."

https://www.motorauthority.com/news/...tion-in-africa

That's awesome. Thank you! It seems like I'm not the only one scouring the web for as much info as possible ahead of these upcoming 2019 models. Danke!!

Bitte. I have read everything I can on the A7 and A6. I hate to say it but the more I read the less I am inclined to get one. Have to wait until the US version is here and we get some reviews of that. Definitely would not buy one since there are too many unknowns but leasing is still an option. Unfortunately it seems like Audi has been raising their money factor higher than any other manufacture I have seen so leasing may not make financial sense. We will have to see of course how things look after introduction. It could be that they after an initial surge, the sales will go down to normal, low sedan levels. I would expect the incentives and MF to come down then also.

Can you please share what about these reviews have left you more and more unsure? As you know, my primary vehicle I'm looking at is the D5, and quite frankly, the main concerns that I have are still present and no review has added to or taken away from that main concern, which is reliability.

I'm probably going to wait until next summer and do a factory order and wait for those incentives. That will also give time for Audi to work some of the things they need to out of these cars, but I can't say that any review has made me go more in the direction of the S class (which is a great machine but I'm not madly in love with it) - whole other story.

Curious what has been pushing you away with respect to what you are learning as each day passes? Like you though, I'm going to place the majority of my decision making process until after I physically drive one of these cars myself.

If I had to put one attribute to each one I would say road/cabin noise for the A7 and ride quality for the A6. Of course the reviews I have read are not for the spec cars we will be getting on this side of the ocean so definitely can't make any decisions on them. It really is more of an overall feeling I get and could be 100% wrong. Until I get behind the wheel and do some driving I will not really be able to say for sure.

As far as not buying, that is just a personal preference of mine. I don't think it is a good idea to buy a car in the first two years of production of a new design. Leasing isn't bad since you are going to turn it in. Just a personal preference.

Road noise and cabin noise are the top things I look for in a car. I believe you're from the US, so please take note for this info. When car reviewers test the A6/A7, they don't usually even know what acoustic side glass is, and they don't even notice or talk about it. It makes a BIG difference. Since you're in the US, you have the ability to pay for an upgrade to get acoustic side glass in the A6. I know that because I was very upset that I don't even have this option in Canada, and based on that info alone, I decided to abandon the A6 and consider the A8.

I'm fairly certain with the A7 you can buy acoustic side glass as well. I know in Canada only the A8 and the Q8 have this as standard, and there is no option to buy acoustic side glass for the other models.

All this to say that all hope is not lost for you. When you do your testing, make sure you test a model with the acoustic side glass. It cuts out the majority of the wind noise, and a lot of the tire noise.

As far as ride quality goes, my thoughts are = air or nothing. I'm so tired of steel springs! That said yes there have been concerns raised about transmission of certain feelings with the air springs on the A6, as I believe you noted upthread. That I don't have anything to add. The A8 - nobody has made those comments yet so it hasn't factored into my decision making matrix.

Dual pane acoustic glass is standard on the Prestige model, whether that is side or just front I do not know. I think every review I have read was about the top model so I assume that it had acoustic glass.

There will also be no air suspension available in the US for the A6 and A7 as far as I know. All of the press say there will only be steel springs but the features listed (not the Build or Order Guide) has active dampers at least.

Damn it. Sorry. I was pretty excited to reply to your post hoping that I may have managed to address some of your concerns. It seems like to me you really know your stuff here and have figured out what you're looking for and what features and such are coming.

Good luck in your car buying process! Just so you know though, on the 2019 Audi A8 in the US, acoustic side glass is an option, even for the top line one. So I believe the acoustic glass you're referring to on the A6/A7 is on the windshield, which is normal for Audi. I'm still fairly certain the side glass is an option. Anyways, just passing that info along in case it helps you in any way :)

I appreciate your info. As far as I can tell from the order guide, build and features list, there is no option for side acoustic glass for the A6 or A7. Best of Luck with your purchase also.

That may be my bad. I may have mixed up the Audi UK build sheet/info with Audi US. I've been on a rapid pace when it comes to learning this stuff.

That said I would still ask a dealer. Why? Because in the United States, the E class, as an option, can be ordered with the Acoustic Comfort Package, which gives side acoustic glass and doubles the insulation in the doors and floor pan. I'd be shocked if Audi didn't either build this into the car (so maybe you're right, and it is built into a package) or it didn't offer it as an option.

In Canada, it's not an option because the BMW 5 and Merc E do not have the ability to specify acoustic glass.

Anyways, all this to say, it's a 2 second check once you take your car out for a test drive. Just stare at the window pane with it down, it's obvious, as you know :)

I have a 2019 Ram Truck with the eTorque engine. It has the 48v battery system in it. I can tell you the stop/start virtually unnoticeable. I have not experience any lag when taking my foot off the break to apply it to the gas. It works absolutely beautifully. So much so, I don't disable the stop/start feature. I would imagine Audi's implementation would be even better than Ram's.

So I test drove a 2019 A8 this past Saturday, one of the first two at my dealership. IMHO, the MHEV / belted alternator starter start / stop system is pretty good. It is not jarring like the pinion starter versions on cars I've rented before. There is a little bit of vibration on restart but from the few times I experienced it during the test drive it wasn't bothering me that I felt I needed to disable it. It felt quick to restart the engine and I tested the "car in front moves" part and it did restart while my foot was still on the brake pedal.

I plan to go back when the A6's start to arrive and test drive again. I need to find another test route for next time which has traffic lights to try it out on though.

I just drove the A8 too. It still pissed me off enough for me to disable it, but you are right, it is better.