Transmission observation...

**rfernatt** · 07-19-2009, 07:25 PM

Since I always drive the smart even though the wife is usually with me, I've never experienced the auto mode as a passenger. Today, the wife drove and she didn't want to use manual since she's unfamiliar with driving it. As I rode and she drove in auto, the auto mode didn't seem to be nearly as 'lurchy' and abrupt as I remember. The 2.0 upgrade has been performed, but I wasn't overly impressed after the upgrade when I tried auto.

From a driver's perspective, the auto mode seems unnatural since you know when you want to shift, but when you're not driving and unconcerned, it seemed pretty decent.

I'll have to give it another try, but will probably stick to manual. But, that's the great part, you can choose either!

fpage77 · 07-19-2009, 07:33 PM

I've always driven in D but not so sure how to drive in manual. I've never driven a manual transmission so how do you know when to change gears.

BigWarpGuy · 07-19-2009, 07:49 PM

I usually drive it in auto mode. With practice, I have found the 'lurch' has become so minor that I do not notice it. I am getting pretty good at it.

I have heard that when to shift appears in the dash where the speed and temp is shown? I do think it is neat that one has a choice to drive in auto or manual.

mvaldes · 07-19-2009, 08:21 PM

AS BigWarpGuy suggests, the transmission tells you when to shift. In manual, and arrow pointing up will appear when it wants you to shift up. And and downward pointing arrow will appear when it wants you to shift down. If you ignore them, they'll shift for you anyway before you get into a range that could hurt your car.
(As you get more used to manual, you probably won't be paying much attention to the arrows. You'll get to know which shift points will give you the best mileage and which ones will give you the best performance.)

Duckhunter · 07-19-2009, 08:22 PM

Quote:

Originally Posted by fpage77

I've always driven in D but not so sure how to drive in manual. I've never driven a manual transmission so how do you know when to change gears.

I have been driving a manual for many years and you just listen to the engine note. Depending on the gear in this car it is between 2500-3500 RPM if you have a tach.

fortow · 07-20-2009, 01:08 AM

The dash tells you when to shift because it wants you to shift at the same engine speeds that the auto programming shifts at. There's no advantage to using the manual mode if you are going to follow that.

You shift a manual transmission when the engine is at an appropriate rpm. What is an appropriate rpm? Well, that depends on several factors - the design of the engine and the gear ratios, and how you want the car to perform are two basic guidelines. For the fortwo, the engine is happiest when shifted above 2500 rpm in the low gears and above 3000 rpm in the higher gears. Of course you don't want to continually redline the engine but it can be done. There really is no point to that with this car though.

So, if you have a tachometer then use it to guide your shifts. Try using 3000 rpm initially and after that you will get to know how you want the car to perform and what the engine sounds and feels like at the shift points you use. You may choose to shift at a lower rpm than that some times and at a higher rpm at others depending on how you want the car to perform. Don't shift under 2000 rpm at any time though.

The auto mode has been programmed to get maximum mileage - it is not programmed to shift at the best rpm range. It tends to shift at an rpm level that is far too low, almost at the point of lugging the engine. You get very little power, the shifts are rough, and the engine vibrates. It also wants to keep shifting to a higher gear even when that is not appropriate. That is one of the benefits of shifting manually - you can keep the transmission in an appropriate gear for the circumstances.

trekguy · 07-20-2009, 03:52 AM

Thanks for the info on shifting points fortow.

I am just about ready to try my shift paddles, and you are right about the automatic shifting; it seems to lug the engine at times and is not very responsive to throttle inputs. I am patiently waiting until my break-in 1000 miles are over so I can zip around like the car was intended.

43.3 mpg on 1st tank!

JD10367 · 07-20-2009, 04:17 AM

The shift arrow is useless (just as it is in my Saturn). If I happen to have it in paddle mode, whenever it tells me to shift is usually the wrong time. You shift by "ear", and/or when you simply need more or less power. In other words, if you're going uphill or breaking away from a red light, you might leave it in the gear longer and let the engine get higher in the RPMs; if you're leisurely pulling away down an empty straight (or downhill) road you might shift lower in the gear to keep the engine from straining unnecessarily.

I've owned a manual transmission for 20 years. I drive the little guy in D for the most part. The only time I take him out of D is at the aforementioned red light or uphill scenarios, or going uphill/onto a highway entrance.

JD10367 · 07-20-2009, 04:19 AM

Oh, and I might drop it into manual with the - paddle if the automatic mode lugs the engine. This happens most frequently if you're cruising down a country road at around 40, and it decides to shift into 5th gear just as you approach an incline.

NCC1701 · 07-20-2009, 05:08 AM

Driving for 38 years, prior to my smart I've seldom driven a manual. So I started out primarily D when I got the car, but over time have migrated to primarily paddle. I've got a record of all of my gasoline/MPGs from day one. My best tank was driving in D, while on a trip to Atlanta. I took the scenic route (back roads) and drove slow ... but, there were hills! For the most part I let the car manage gear changes over the hills. And, I STILL came out with my best tank yet. Maybe it was more due to the slow speed and lack of jackrabbit starts (I'm a lead foot).

I put in a little D driving time in town yesterday for the first time since I got my 2.0 upgrade. Probably because I wasn't in a hurry and was being gentle with the gas peddle, but it does seem like the shifts are smoother than they used to be. It also seemed to wait to shift to 5th gear a little longer than it used to. For what it's worth, according to SSII, I seem to get my best MPGs when the engine is running around 1,500 RPM on level roads. At that engine speed you get a bit of the lugging sensation though. Others have stated that it isn't really lugging at that speed but it doesn't sound happy to me. ??