Any tips for driving a small car with automatic, getting it to shift right.

[cobb]

I learned to drive on a dodge neon and drove a yaris rental car the other day and just was driven crazy by the auto transmission. Basically both would sound like you were driving like a bat out of hell from a dead stop, with little throttle presure as it ran through the gears. Once you hit 40, seems you need more than 3/4 throttle movement before it would upshift and accelerate as swiftly as it did earlier. The ford e250 van I drove, which also had an electronic transmission would up shift as needed and by throttle position in a reasonible manner. I could make up leave od bygiving it 1/4 throttle and to 3rd by giving it half throttle.

Glad I have a stick shift and makes me think more of a car with a cv tranny vs 4 or 5 speed automatic next time around. Nothing wrong with my car, just wanted to get something checked.

 

[gadget_lover]

Most small cars with a small, low powered engine and auto tranny need to rev high to stay near the power band. Rentals frequently have the smallest engine that's available.

If you think back to the previous posts on transmissions.... as you shift up you are trading speed for power. The engine only creates X power at a certain rotation. That power is REDUCED by the gearing in direct proportion to the increase in rotational speed. So a 100 ft pound motor in 5th gear may only be delivering 20 ft pounds to the wheels at 65 mph.

Taking this into account, when you are doing 40 and hit the throttle, it does not have the TORQUE to accelerate swiftly. And it's shifting DOWN to a lower gear if you press the pedal far enough. Down-shifting means lower gearing (more torque) and higher RPM (more power generated).

It's one of the things I love about the CVT / electric mode in the Prius. It's always in the power band due to the CVT and always has that extra torque from the electric motor on tap. This makes up for an engine that is significantly weaker than the Yaris.

Daniel

 

[cobb]

Well, gadget I do understand the power vs speed thing, but why would an electronic controller tranny in a 4 bangger with a higher power band refuse to upshift unless absolutely necessary where as the cargo van did it as needed or even going up a grade?

Am I missing something here? Why didnt the 4 banggers upshift to 3rd or second if I am going 40 up an over pass and had my foot 3/4 to the floor and was slowing? Was this not done for fuel economy vs performance?

Just trying to make sense. If I didnt need two hands to drive, I would of continued to shift it by hand.

 

[270winchester]

you are not missing anything. These sub-subcompact cars are designed to be commuters and city cars and the auto transmission is tuned for fuel economy and get this, when they are tested for EPA rating, they are generally on a flat surface!!!!(last I heard) and get this, they are tested at around 50 MPH for the highay rating, so it's in their best interest to delay the downshift as much as possible at the speed you are describing(over 40) to maintain a high milage

SO these cars have a helluva hard time up hills and you do need to decide to save gas by letting it slow down a bit or punch it and make it speed up on an up hill, simple physics and reality in a small engined car.

the cargo van you had probably had a V6 or bigger and those things have a lot more torque even at the cruising RPM range, it's copmaring apple to oranges in terms of performance characteristics.

I'm not familiar with the Yaris but in most recent small compact cars I have driven, the car would have 4 gears adn the 4th is overdrive. If you are going up a large hill one simply has to switch off the overdrive and the car will not using any gear higher than 3rd(or whatever is lower than overdrive) and thus can go up hills a little easier.

 

[Fallingwater]

There are plenty of Yarises around here, and let me tell you, the words "horsepower" and "yaris" shouldn't be in the same sentence, at least not without the words "lack of" somewhere in between...
They are all stick shifts around here, and for good reason.