As said, in snowy conditions you really want winter driving mode which will start the car in 2nd gear rather than first, to reduce the torque to the drive wheels. Many sophisticated auto transmissions have that feature.
Automatic transmission are great in many situations, better than most humans in shifting while accelerating from a stop. They are more efficient and faster. But there are some situations such as in snow and on steep hills where an automatic doesn’t have the intelligence to do things as well as a human. Many folks are fine with that, but there are times you want to add input into the system that the car can’t figure out for itself. That’s all the manual override on the transmission allows you to do. You’re giving the transmission more information that it has no way of knowing.
It seems to me that “OD off” buttons confuse the issue; I’d rather just have a shifter than went 4-3-2-1 rather than a button to go 4-3 and then a shifter. I do use lower gears for going up or down hills or when I want extra power for passing or merging, I’d be extremely upset if they removed the option from automatics.
Because its really the length of the hill that is the problem.
How is the car going to know the length of the hill ?
A long hill may cause your brakes to overheat. Your engine has a temperature control system, and a backup and anyway if it overheats it doesn’t cause loss of control .
You don’t want to overheat your brakes.They fade.. They stop working.
Mercedes do have a brake temperature warning light, but many other makes don’t.
In snow, use snow mode if you have it, or ‘2’. Or modern cars have full time traction control. (Mandatory on new cars in Australia.)
Snow mode if it locks to a 3 , etc, may well limit engine RPM’s and limit gear changes.
Using ‘2’ does limit gear changes (won’t change to 3 or higher), and means that even if the engine red lines, the wheel speed is limitted.. as 2 is a slower gear.
Prevent the change of gear to help avoid breaking traction due to wheels feeling the effect of the requisite change of engine RPM.
Limit wheel speed, to limit wheel momentum. A wheel spinning way too fast might touch onto grippy road surface and cause loss of control.. oversteer, eg fishtailing.
Manual transmission is still very much of today - many drivers prefer it and many places (though not in North America) require that you know how to drive stick before they’ll give you a driver’s licence. Good luck renting a car in Europe if you don’t know how to drive stick.
Automatics with the ability to retain some degree of gear control seems to be what people want, as this is what they have. Adding further gear choices is less popular but still available on cars with a “sports” transmission. Removing gear choices completely doesn’t seem to be desired.
Everyone is bringing up the utility of lower gears for controlling descents. My experience has been that the ability to hold the transmission in a lower gear is also useful for ascending mountain grades. If you’re climbing a long, steep grade, the transmission may have a tendency to upshift-then-downshift repeatedly:
you start climbing a steep grade.
car begins to decelerate.
you press the accelerator further down.
car downshifts, RPM’s go up, engine is now making enough power to accelerate.
car reaches target speed, so you ease up on the accelerator.
car upshifts.
Repeat steps 2-6.
They way out of that cycle is to use the PRNDL selector to hold the transmission in a lower gear. People who have never driven outside of the eastern United States probably haven’t seen roads lke this, but once you get into the mountain ranges of the western US, you see plenty of them.
I use a lower gear when I’m towing a trailer in my Jeep and have to get over a steep mountain. I’ve been on trails so snotty with mud that the only way to get up the hill (or down it) was to be in 4WD Low Range. Lower gears are also useful here in the lowlands when it snows. Of course I’ve had to shift into lower gears in underpowered standard-transmission cars when going uphill.
Re: Overdrive. The MGB’s overdrive is engaged by flipping a toggle switch on the dashboard.
Exactly. I’ve never owned a car with an automatic transmission. First time I ever encountered one was when hiring a car in America. Made me feel pretty stupid as I had no idea how they worked, so a bit of trial and error in the car park was required…
Note that the low gears are present (and necessary) in all transmissions. It would be possible for a car to prevent you from manually selecting them, but would not be possible to omit them.
Mine is conventional. It doesn’t have a 1 or 2 (or S and L, as they used to be labeled). Instead, you push the shifter to the right. There is a + and - to set the gear, so it actually could be used to be in third gear if you needed it.
My Volvo had a “winter mode” that skipped first gear and started the car moving directly in second gear from a stop, so as to apply less torque and theoretically cause less risk of spinning the wheels on a snowy surface.
The worst hill I know in the North Jersey area is Rt 280 downhill from West Orange to the Parkway. Max 6% grade for about 4 miles, I think, but it varies between steep and not-so-steep. I’ve never downshifted, but I don’t ride the brake the whole time either. I let the car accelerate to to about 55-60, and then slowly get down to a little under 55, and repeat several times. Is that harmful?
I’ve always presumed that downshifting is for mountains that are much longer or much steeper than that. Fight my ignorance, please!
That’s a sequential manual or semiautomatic, depending on where you are. That’s not a utilitarian feature; it’s to let you change gear yourself for fun.
No, it’s probably just an automatic that lets you shift for yourself (manumatic, very common these days). Semi-automatics and sequential manuals (I’m not aware of any passenger car, past or present, with an SMT) are totally different beasts.
It’s kinda both. My Kia Sedona has the same shifter, as do all Kia/Hyundai cars of the era. Manual-shift modes were a big marketing thing a few years back, so they created the +/- automatic shifter thing for their “sportier” (heh) cars. And then they put that same shifter in every car they made, which is how I ended up with a minivan with “sport shift” or whatever they call it.
It’s a conventional 5 speed auto with PRND options. When I’m going down a hill and I want to kick it down a gear, I have to move it over to the manual shift gate and shift down to 4th or 3rd. You’ll just have to trust me that I’m not doing it for entertainment :), and I’ve never manually shifted my minivan for fun. It’s strictly utilitarian in that car, since it’s the only way I can force a lower gear. I’m guessing they just dropped the 2/1 options from the conventional gate to save money.
Several times? Probably not. Your brakes cool enough between uses to not overheat your brake fluid. Dozens of time? You might run into problems.
I occasionally drive up and down the Mt Washington Auto Road in NH. The drive is 7.6 miles and drops 4600 feet though windy turns and steep drop offs. My car is a standard but in any car you need some way to force the car into the lowest gear. There are some models that aren’t allowed on the road because they can’t limit themselves to 1st.