Comments - The Key to High Mileage: Understanding the Smart transmission - 451 smart fortwo

I have noticed that if the ca…

2010-05-14T18:52:37.425Z

I have noticed that if the car isn't perfectly still when changing transmission selection, the little gearbox goes into a "protect" mode. It keeps you from busting gears if you put it into reverse while inching forward, and vice verse. You have found the fix (reset). Smart also recommends that you engage the hand brake before going into, and after coming out of Park. Just my experience - hope it helps.

Enjoyed your video, especiall…

2010-05-14T02:31:24.732Z

Enjoyed your video, especially the hat.
Thanks for the advice about getting out more. When I got my Smart Car, I never sold my Scion (my BIG car) so I use that for trips outside the city. ;-)
I think my transmission problem is NOT like yours. My on-the-floor style shifter has never been hard to move, but although it slides easily into the gear, the car won't move, sounds like it's in neutral. Dealer did a complete check and assures me there's no sign of unusual wear and tear on my clutch. He doesn't think my driving always in Manual mode is the problem. So I'm at a loss.

Hi Rebecca, I also used MANUA…

2010-05-13T04:18:20.629Z

Hi Rebecca,
I also used MANUAL a lot at first and I got progressively stiffer shifts. I think the folks at Smart in France didn't use the right lubricant on the shifter assembly. My quick and dirty fix was to spray some lithium lube into the shifter lever gaps. It worked perfectly. The problem was in the handle, not the transmission. Later on, when I had my 20,000 major maintenance done at the Riverside dealer, they relubed the shifter. They wouldn't have done that if they didn't know about the problem, which got pretty loud on the Internet. I also had the new shifting program downloaded, which I regret - but just a little.

Honey, you gotta get out and taste the world in that little car. It's a blast! You live on one of the best drives in the world. Go for it. Do something wonderful like this. http://www.newplague.org/Flash/output.htm

Hi Rick, Just discovered this…

2010-05-12T18:06:46.136Z

Hi Rick,
Just discovered this March 2008 post about "Understanding the Smart Transmission", which I confess I have never understood. The dealer upgraded my transmission software in April, 2009, but I have always used the Manual mode, because the shifting was so much smoother. I've only gotten about 25 mpg, but I assumed this was because I do ALL my driving in San Francisco and there's a stop sign EVERY block, plus very steep hills. I don't travel very many miles (about 250 miles a month) so I don't really care about the low gas mileage.
But now I'm having a problem with my transmission: Twice in the last week when I've shifted into Reverse, Drive, or Manual Drive, nothing happens. Car won't move, it's just like it's still in Neutral. After I turn the car off, this problem fixes itself when I turn it back on, so I've assumed this is a transmission software problem, but your post made me wonder if my driving might be to blame.
Took it to the dealer who is replacing the Clutch plate. After reading you post, I wonder if this problem could be the result of my constant use of Manual mode? I'd really appreciate any ideas or suggestions you might have. Thanks.
Rebecca

Sure, stress is the agent of…

2010-02-08T18:36:09.826Z

Sure, stress is the agent of engine wear. Think of the force footprint of a piston impulse after ignition. All that force is concentrated on the downside of the wrist pin and upside of the crank journal bearing. Whatever load you are pulling is fighting against the piston force. A good driver moderates that force by using gearing. By shifting earlier when pulling a load, you put less stress on the engine. To really baby that engine when pulling a load, instead of putting your foot in it you accelerate proportionately slower than you would when empty. For instance, with a loaded pickup, take twice as long to get up to a certain speed than when empty.

Another thing that makes our engines last longer are automatic transmissions. Automatics distribute forces on the drive train better than even the best driver with a manual transmission.

That said, any silica (dirt) in the oil will wear away those mating surfaces no matter how the vehicle is driven. Theoretically, good oil prevents metal surfaces (within tolerance) from contancting each other so engines, transmissions and rear ends should last forever. Unfortunately, dirt gets in when maintenance goes down and cars wear out. Once dirt takes the contacting surfaces out of tolerance by making the gaps too wide, that footprint I mentioned begins to reshape the metal surfaces by grinding them together, then it is only a matter of time before you have a failure.

That's why new cars are a real opportunity for someone who understands this to have a car that lasts a lifetime. Synthetic oil combined with high quality metallurgy we see in some of the imports like the Lexus 400 series are rewarding their owners with in-spec tolerances beyond 500,000 miles.

For the old stuff like your truck, don't waste your money on synthetics. Just change all the filters frequently, including the auto transmission filter, change out the rear end fluid each year and run multi-vis 10-40 with the current API ratings.

Very nice post! I drove a tru…

2010-01-10T16:46:23.777Z

Very nice post! I drove a truck in college - and old Detroit 318 2 stroke V-8 diesel with a 13 speed transmission - so I can appreciate your explanation. However, I suspect the Smart Car uses the clutch for each shift, even though the computer waits until the engine speed is matched to the gear speed before making the shift. It would be asesome if it were making the shift sans clutch, but I suspect this is not the case. (Wonder how this could be verified for certain?) Thus the big delay between 1st / 2nd shifts. Having driven stick shift cars most of my life, I am completely impressed and amazed with the way the Smart Car operates the clutch and 5-speed!!! Whenever I read some journalist dissing the transmission, I just shake my head. It reminds me of the neighbor kid in my old pickup that couldn't figure out how to roll down the window - because it had a hand crank and not a button!! I commute 110 miles round trip in Houston and mostly use the automatic feature getting between 40 and 44 MPG even with the A/C on. Mixed stop and go and freeway. When driving at 70 - 75 for long distances the mileage drops to the mid to high 30's. About the only time I use the paddle shift mode is in traffic situations where I prefer some engine braking at low speeds rather than using the brakes and letting the computer make unnecessary shifts. One nice thing about the automatic mode is that when approaching a stop, you can pop the tranny into neutral and coast for a couple of blocks!

As 3/4ths of my driving is on…

2009-09-07T23:14:40.825Z

As 3/4ths of my driving is on freeways between 65 and 75 mph I don't feel bad about the 38 mpg I get overall. I generally use manual mode with full throttle upshifts between 3k and 3.5 k rpm. I haven't been in much stop and go traffic as a traffic jam in South Bend is generally only about 5 to 15 cars and usually takes one or two light cycles to get through. When my wife and I are touring on back roads the milage usually goes up by 2 to 4 mpg if freeways aren't involve. I have found the downshift switch and try not to use it, preferring to drop down by 2 gears most of the time at corners, or just stop the car. Seems there have been several surplus stop sign sales in the area!

I consistently achieve better…

2009-03-26T22:22:05.444Z

I consistently achieve better than 50 mpg on windy, hilly secondary roads using the constant throttle technique on level and uphill stretches, and coasting on mild downhill, and using auto for steep downhill. And yes, avoid the brake when possible as you are effectively turning gasoline into heat instead of mileage.

Perhaps some of this starts t…

2009-03-26T19:51:01.625Z

Perhaps some of this starts to explain the reasons why some owners report such dismal mileage, and perhaps also lends a thought to why the EPA rating is so much lower than the cars usually actually achieve in mpg.
However none of this addresses one particularity I've noticed about the transmission. While in "auto" mode and accelerating very quickly from a stopped position, when the gas pedal is let off to reduce the rate of acceleration the transmission does not shift into a higher gear. Instead it stays in a neutral position while the engine races at high rpm. In certain traffic situations I put mine into manual mode, when I'm going to accelerate quickly from a stop and when I know the terrain will work against the inclination of the auto mode. Of course sometimes I use that mode for fun as well.
However, without exercising care with regard to acceleration or speed I very consistently achieve fuel economy (42mpg) above the high end of the EPA estimate. Less than 15% of my driving is done on highways. Most of it is on open country roads in hilly terrain, through small towns, and each day some limited time spent in traffic jam situations. These jams always occur on the highway part of my commute. It is somewhat surprising to me how little I use the brake in this car, but then I'm not an "ass rider", I always keep a decent cushion between me and the next vehicle in front, more if there is an "ass rider" on my tail.

excellent posts! these will h…

2008-12-20T13:28:01.571Z

excellent posts! these will help me. I go to pick up my used 2005 fortwo cdi this morning.