Driveability Issues with Advanced Powertrains

[The Critic]

http://blogs.insideline.com/roadtests/2011/03/2011-chevrolet-cruze-ltz-cruising.html

Some lines from the blog entry:

Quote:
None of this really makes the Cruze undrivable, of course. Most people would probably never notice this behavior, which is why it’s so hard to describe. It’s one of those development things, where more time is needed at the proving ground to find a way to effectively balance the inputs from the engine, transmission and throttle pedal.


Quote:
What worries me is that we’ll soon be driving a lot more cars like the Cruze — cars that are trying to find the balance point in powertrain performance under the constraint of extreme fuel-efficiency requirements.


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Now automatics like this one in the Chevy Cruze almost seem as if they have been engineered to maximize shifting, attempting to keep a car poised at the balance point of maximum fuel economy.


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If the Cruze is any measure, some development problems lie ahead.


The last turbocharged car that I drove, a 2011 GTI with the DSG, exhibited none of the issues described. The issues mentioned seem to be a trend lately, that plague economy cars that are tuned for maximum fuel economy. And it also seems that the issues have hit some of the GM cars worse than other makes, based on the number of complaints about GM transmission programming.

 

[bullwinkle]

The Cruze available with a manual transmission?

 

[justinf89]

I personally like staying at the best speed and gear for fuel economy. Of course the best I ever see is 25mpg. I could see where it would be a nusence though.

 

[GMBoy]

This is a direct result of CAFE and other regulations. GM will probably offer re-flash if enough people find it annoying. I am also sure the aftermarket will offer power tunes, too.

 

[d00df00d]

Originally Posted By: The Critic
The issues mentioned seem to be a trend lately, that plague economy cars that are tuned for maximum fuel economy.

Well, yeah. When you're going for peak MPG, the engine is going to have very few and very narrow sweet spots in the RPM and throttle ranges. That means the transmission needs more gears and will have to shift more frequently in day-to-day use. Unless the transmission is impeccably programmed and shifts absolutely perfectly every time, it's going to get very annoying.

CVTs would solve everything, but people don't want them because they don't like the sound (one RPM all the time) and/or the feel (no shift shock). I think that's beyond ridiculous, but that's just me.

The only way to have these levels of fuel economy without these kinds of powertrains would be to have drastically lighter cars. We can't have that for safety reasons, because there are so many SUVs floating around.

No one to blame but ourselves...

 

[Hokiefyd]

My 2011 Camry exhibits some of the same behavior, but I rather like it. It doesn't feel "unrefined", but there's also no slippage in the transmission when it shifts. It's a very positive shift with little waste. And when coasting, it keeps the TCC engaged and cuts fuel, so there's a lot of engine braking.

Compared to my former '07 Town & Country and '97 Dodge Dakota, there's a huge difference. Those automatics could honestly be called "slushboxes". It didn't matter what you did with the throttle pedal. There was a smooth (but also muted) response back. The penalty for that is increased heat and reduced economy.

Ironically, because I enjoy driving manual transmission cars so much, I appreciate the way my current transmission operates, and I'd probably appreciate the way the Cruze operates also. You have to be smooth with the gas pedal, just as you do have to be smooth with a manual. The only difference, really, is the lack of a clutch. When you look at fuel economy ratings now, most automatics match the economy of the manual transmission option, so it's clear (to me) that these measures work. Would it be annoying for an unskilled driver who treats the throttle as a binary switch, either on or off? Probably.

 

[JHZR2]

Originally Posted By: Hokiefyd
Ironically, because I enjoy driving manual transmission cars so much, I appreciate the way my current transmission operates, and I'd probably appreciate the way the Cruze operates also. You have to be smooth with the gas pedal, just as you do have to be smooth with a manual. The only difference, really, is the lack of a clutch. When you look at fuel economy ratings now, most automatics match the economy of the manual transmission option, so it's clear (to me) that these measures work. Would it be annoying for an unskilled driver who treats the throttle as a binary switch, either on or off? Probably.


Thank you. Nobody gets this. Appreciate and understand physics and the motion that is part of the acceleration pattern when done properly and there are no issues. Of course everyone thinks that they "deserve" a "spory" vehicle, and so you get these vehicles out there that are neither efficient or truly sporty, just ridiculous things that are geared poorly and dont operate well.

MTs should be required unless you are handicapped, if for no other reason than so that people can have some basic understanding of how to drive besides mash the go pedal.

 

[sciphi]

Or get a manual transmission. Then you have yourself to blame for bad shifts.

I didn't feel/experience anything wrong with the Cruze 1.4T I test-drove. Too bad the only manual available with that engine is the Eco version.

 

[The_Jeff]

This came up with the Equinox and its fake 32 MPG highway rating. They put in a sharp decel fuel cutoff that bugged people so they reflashed it out... after they got that magical 32 EPA number.

 

[cheetahdriver]

If you grew up with a 3 speed, the behavior of a 6,7 or 8 speed automatic is going to be confusing. It is going to shift quite a bit more, it is going to try to keep the engine in the best economy band unless you are romping on it and then it will shift to best power. I have a 2011 Town and Country minivan on rental at the moment while the radio shop works on the plane, and the combination of the Pentastar engine and a good 6spd transmission is quite pleasing. It doesn't quite get as good of gas mileage as I expected (although someone else would probably get better), but it is quite responsive on the throttle. With the addition of computer controls and more gears to the automatics, I see this only getting better.

Of course, I always have the manual Miata for when I want control. Guess what? The 6spd manual there requires more shifting than a 3spd too....

 

[Chris Meutsch]

Originally Posted By: d00df00d

CVTs would solve everything, but people don't want them because they don't like the sound (one RPM all the time) and/or the feel (no shift shock). I think that's beyond ridiculous, but that's just me.


I got a chance to drive a 2010 Altima rental with this transmission and I loved it. Took a bit getting used to sound-wise, but I sure got great mileage on it.

 

[IndyIan]

Quote:
The days are gone when an automatic transmission minimized shifting and was meant to deliver a long pull of seamless power.

This is how my Neon feels with the 3 speed auto, at 40-50% throttle it will hold 2nd up to about 55 mph and 4200rpm(it starts to sound abit loud at 5k+ rpm) and your motoring up to 60 with the shift to 3rd and TC lock up.
I actually like hearing the engine rev up a bit and I might as well get up to speed quickly as it only locks the TC in 3rd...
I almost think a small displacement turbo motor might do better with a 3 or 4 spd auto in terms of driveability, holding each gear longer lets the boost do its work, and there is hardly any fuel penalty revving up a 1.4L.
Also it should be able to build torque with boost at lower rpms if the trans will hold top gear at 30-40% throttle.

 

[NateDN10]

Seems like it's just the nature of the beast. You can't have great fuel economy and performance.

 

[Jim_Beverlin]

I rented a Dodge Caliber with a CVT for a business trip to Chicago last year. Thought it was ideal for this vehicle. Gas mileage was not that good but Calibers to not get outstandling fuel mileage.

 

[kb01]

Originally Posted By: JHZR2

MTs should be required unless you are handicapped, if for no other reason than so that people can have some basic understanding of how to drive besides mash the go pedal.


I used to feel that way. Until I moved to Pittsburgh, which made a standard transmission an annoying chore.

 

[jim302]

There is nothing wrong with an automatic transmission. Not everyone wants to deal with constantly shifting in traffic when you hit every stoplight red.

I like automatic transmissions that still give you some choice in selecting the gear. Some cars offer this as part of a sport package, and some offer this feature standard. This lets you get past the gear hunting and improper gear selections that are at times inevitable with any automatic.

Honestly, from reading the article, I didn't see what their complaints were. I haven't driven a Chevy Cruze, but it is an economical car... nobody is buying it for the power.

 

[rslifkin]

I do like certain things that newer transmissions do, such as keeping the TCC locked when letting off the gas. I really, really wish my Jeep did that, as the bit of flare when you get back on the pedal after coasting at 40+ mph is annoying, and it probably puts a good bit of wear on the TCC itself. With a higher stall torque converter, my transmission is an absolute slushbox, but at least it's pleasant and predictable in how and when it shifts.

Newer autos have come a long way, they (and the engines they're paired to) just need a little tweaking to optimize torque curves and corresponding shift points for good economy without being annoying.

 

[Craig in Canada]

What I read of that article seems to explain why I hate all automatics in general, not something specific about the Cruze...

The authour seems to dislike any ATs with a larger number of gear ratios and dislikes shifting at all. The addition of more ratios and more TC locking is the only thing which has made some modern ATs (like those used in BMWs) tolerable to me.

 

[rslifkin]

TC lockup definitely makes an auto nicer to drive. I don't mind having only 4 gears in mine though, as the engine has a wide enough powerband to be happy.

 

[SteveSRT8]

Variable lockup is the key to a satisfying automatic experience.

4 gears is plenty if you have enough stall speed and can lock the tc incrementally.

Many newer slushboxes do this.