In an automatic car what is the difference between. D,D2,D3,and D4. I always use D4 but i don't kno the difference between them.

D uses all 4 forward gears. D3 used gears 1-3. D2 uses 1 and 2. Most people never use anything but D.

thanks i didnt know this. now what is the benefit of using somethign like d2 or d3 does it save wear and tear or gas or something?

D uses all 4 forward gears. D3 used gears 1-3. D2 uses 1 and 2. Most people never use anything but D.

I might be wrong, but I believe that D and D2 use only their respective gears. Such as D willy only use 1st gear while D2 will only use 2nd. I've driven around in D2 before and even under WOT it is still very laggy until about 35mph.

Most times you would only use the lower gears for compression braking downhill, like if you don't wanna be overusing the brakes on a mountain pass....I'll shift down to D3 in some long downhill areas where cops are known to sit and shoot radar, just to keep the speed down around the limit without riding the brake...

A lot of cars incorporate a second gear hold feature, so when you put the car in "2" it starts from a stop in second rather than first...this is helpful for example if you found yourself spinning trying to leave a stop while faced uphill on a snowpacked road, the lower torque and muted throttle response of starting off one gear too high will allow the tires to get traction without trying to break loose...but you want to shift back into a drive gear once moving above 25 mph or so...

Likewise, a lower gear selection can give you control of vehicle speed downhill in poor traction conditions....there is a hill at my MIL's in the country that if snow covered, it would be suicide to try to brake down it, you'd loose control of the car and go off the embankment if a wheel locked up on you...road is cambered wrong and everything, real nice...

I just blast my way to the top, and right before the peak I drop the gas so it rolls to a stop at the top, then put it in "1" and let it start to creep down, with the engine holding it back....you won't get higher than 15-20 mph like this...then gentle steering inputs when a correction is needed, and you reach the bottom in control and safe...

You'd be amazed how many people have ate it on that hill...they get up to 30..40..50 mph, start to panic...loose their nerve, stab the brakes, lock up, and off the road they go...or try to ride the brakes down it and end up getting sideways, then panic...

That's the beauty of knowing how to use your gears...there's no reason why you shouldn't in an auto just like a manual, but for some reason a lot of people have this (incorrect) idea that it will hurt the tranny...

It comes natural to me as a semi driver....we can't ride our brakes downhill, or they'll overheat and stop working...we just use the correct gear for the hill, and use momentary strong stabs of the brake to bring it down to the desired speed...riding the brake (in a car as well) builds heat, and doesn't use all the wheels evenly, leading to overworking some wheels, which is bad....in a lot of cars, one rear wheel's brakes don't even lift off the stops on light applications...in an eighteen wheeler you have brakes on 5 axles, ten drums...you want them all working together or you get some really assymetric braking force, which can get you in trouble...

Sorry for the lecture. Oh yeah, stay outta the big rig's way...we couldn't stop if we wanted to downhill...lotta people don't realize that...once we start down, we're committed...ain't no stopping...

That was a very nice read Jeff. Good info that I didn't know in there. The only problem is the Hondatragic of the 6th gen V6 trannys.