Just got my 03 g35 auto....havent had a manual mode in a car yet...did a search and found some helpful info but not exactly what I am looking for...

If I am in drive....can I just flip it over to manual mode at any time? same with MM...if I am in 5th gear and wanna go back to auto do I just sent it back over to D?

And lastly on hwy in 5th gear and traffic ahead should I just brake and let it downshift itself?

thanks

Yes on all 3 counts.

yep
yep
it won't downshift as you slow down. It will go back to first gear when you are stopped(or moving at about 1mph). If you slow down to 20, and decide to take off again, you will still be in 5th gear.

Just tried this out. If you're on 5th gear, and getting too slow, it will shift down to 4th, then 3rd, then 1st (it will skip 2nd) automatically.

Doesn't sound much like a manual mode then.

It really can be just "manual" on the upshifts...where it matters most. Just as the rev-limiter is in place to protect the engine from bad driving, the automatic downshifting in manual mode serves the same purpose.

Personally, I downshift myself 90% of the time when using the tiptronic feature - which is about 90% of my driving. In my opinion, if the transmission wasn't engineered to operate in this fashion, Infiniti wouldn't have allowed the user to operate it like this. To date I have 53,000 trouble-free miles - with me driving the last 27,000 miles.

I know this will probably draw some criticism, so I'll add this in advance. Infiniti warrants the transmission for 70,000 miles, so if from day one a driver used the manual mode to its fullest, Infiniti-limited potential, Infiniti still expects the transmission will last 70,000 miles...or few enough of them will fail to make the replacement cost cheap relative to building a stronger transmission.

Perhaps someday my transmission will fail while operating it within the parameters Infiniti allows. I suspect that by the time it does, if I still own the car, the value of the g35 will have fallen in value to the point where it isn't worth replacing.

On the other hand, if someone doesn't have the ability to write a check for a new transmission without worrying about paying their mortgage or putting food on the table, one might want to operate the transmission as conservatively as possible.

^^^

I've heard that it's not the transmission that gets damaged, it is the torque converter. If you are going 55mph and you down shift to 2nd gear, it may damage the torque converter. That is what I have HEARD from some members here. I don't know if that is entirely true. Hopefully someone can elaborate on that.

I don't know if the computer will allow a downshift into second at 55 - I don't think I've tried that. I do know the computer will allow a downshift into first beginning at 28-30 m.p.h., but not above that.

I wonder what redline speed is in second gear? Doesn't seem like it would be much more than 55 m.p.h.

I should probably write that there's a difference between occassionally operating a machine at the limits that are prescribed by either computers or physics, and constantly operating a machine at those limits.

Another thing for the OP, when you select manual mode while cruising at speeds above 35 m.p.h. or so, the transmission will automatically downshift into fourth for you. This is an easy way to quickly select a lower gear when you need to pass someone.

Yeah, Infiniti designed a too smart manual mode that will prioritize protecting itself first over the driver's desire, which I guess is a good thing, but makes me regret not being patient and getting a 6mt instead.

You wouldn't have asked this question if you'd considered everything involved, stress on your engine and trans. If you've driven your G35 enough you'd know trying to drop into 2nd at 55 MPH would be a bad idea, even if it was possible! My guess it you'd be over the rev limiter. I wouldn't drop into any gear lower than 4th going 55 and then only if braking. I hope a little common sense prevails here or you could destroy your ride....
Gary

If I'd known at the time my wife would ultimately prefer driving her "monster truck" Grand Cherokee to the g35, I'd have bought a 6mt as well.

Sorry, that was just an extreme example. I know the ECU won't let you down shift if it is not safe. Let's say if you down shift from 3rd to 2nd when you are going 35mph, you will feel that the car is being pulled back. Does that damage the torque converter?

^If done continously for years, your adding more wear on it and will eventually shorten its life a little.

Our M5 even downshifts automatically if your speed is too low for a given gear...

There's no sense trying to get the car to drive at 5mph in top gear, it'll just kill the torque converter (or clutch if you have a sequential manual)...

I don't know if the earlier coupes have a DS (Drive-Sport) function, but the 08 Sedan I was given as a loaner did.

In DS, if you were driving "spiritedly" and had your foot down and were doing say, 110mph in 4th, as you braked to enter a corner the transmission would actually rev-match downshift into a lower gear when your speed dropped down enough, so the RPM's never fell below 3000RPM.

So I can't see this being such a huge problem if the car does it automatically.