ladrainian21

Hey guys, first post as I am a first time owner of a Merc. I recently purchased a low mileage 2009 C300 Sport 4Matic as my first "real" big boy purchase out of college. I've done some searching here and read this section in the owners manual and I'm still a bit confused. I don't want to play around too much with touch shifting without knowing what I'm doing as I don't want to jack up the tranny. I'm coming from a stick Mazda 3 but this is obviously different.

What I don't understand is the D+ D- and the number that appears for D+. Say for example I wanted to floor it from first on a straight away. What D+ number would I want? I know if it redlines it will auto shift up a gear but if I wanted to max the rpms before shifting what would be the best process to do this? What does tapping the transmission to the left and right do? From what I understand when downshifting the car limits the gear selection to what is allowable for the current RPM.

I understand this isn't a race car that's not what I bought it for but I'd like to know what I should be doing for times when I want to play a bit on empty back roads or for passing on the high way and occasionally maybe messing around at stoplights.

TLDR; can someone please dumb down the owners manual for me and explain to me how to launch properly from slow rolling/standstill and how to pass and decelerate without messing up the transmission.

sagar526

There should be a m/c button next to the gear stick. Press it for to change between full auto and manual. Full auto does as it sounds and will change as it pleases. Manual, you can stick to a certain gear and go up and down as you please. Ideally to launch, start in 1 in manual and redline it throughout the gears. Also, if you tap the gear -/+ while in full auto it should show on your dash, D1, D2 D3 etc. This will hold gear one, gears one and two and gears 1 2 3 respectively.

ladrainian21

I have a s/c (sport and comfort button) so I'm unsure what you're referring to. The s doesn't put it in full manual mode at least for me

Rodpwnz

To anticipate passing and to get yourself in the lowest gear possible, hold the gear to the left for a second. This will put you in "tiptronic" shift mode where you manually control the gear changes, and it will put you in the lowest gear possible. After you use the feature to pass or merge, you can then nudge the stick to the right briefly to shift up, or hold the stick to the right for a second to go back into auto mode. If you stay in tiptronic, you can shift left or right to change gears accordingly. This mode of shifting will feel very sluggish and slow compared to stick or other comparable "tiptronic" modes.

From my experience in the back roads, if you feather the gas in "tiptronic" and keep it at high RPM (4500+), the car will jerk back and forth without any ability to control it. It is not a pleasant experience and can be dangerous. The jerking really shows that Mercedes did not intend for the tiptronic mode to be used aggressively. From the last time I went, simply keeping the car in auto mode when aggressively tackling the corners will allow it to quickly learn and adapt. I have been pleasantly surprised when my C300 would keep me at 3,000+ RPMs when I was on mountainous roads and taking corners where the power helps carry you through. I was mostly on uphill when it did this though. It may have something to do with constantly being on the throttle, at least a little bit on the throttle.

As you may have noticed, this is not the norm when taking corners. Usually, power will cut out during a corner and then it will kick in immediately after the corner is finished, which is not ideal. For single corners or passes, I would say put it in tiptronic. For multiple corners or windy roads, auto works best for me. I usually use a mixture of both on the windy roads.

I've recently timed my 0-60's and I found my best time (7.0 sec) was when I put it in tiptronic and just floored it. The S and C mode only differ in what gear you start with in auto mode and I believe the shift points. Sport mode starts you in first gear, while comfort mode starts you in second. For responsiveness and sportiness, always choose sport.

If you also want to have a little more responsiveness from your transmission, you could try a TCU reset. Your TCU will adapt to your driving habits after some time, so unless you are going WOT at every light, your car will adapt to a relaxed driving style. I usually reset my TCU before a day on the back roads.

Here is a thread on how you reset your TCU, please be sure to read Chokaay's modified instructions:

https://mbworld.org/forums/c-class-w...esponsive.html

michail71

Unless you have the dynamic handling package the car isn't designed to be manually shifted. You will have the paddle shifters on the wheel if it has that option.

Otherwise the shifter lever is just for limiting your top gear for driving down steep grades such as driving down a mountain. In some ways it's similar to manual shifting but different.

ladrainian21

Thanks for the detailed response. Also I had read about the TCU reset but wasn't exactly sure at the purpose behind that so I'll give it a try! Love your car by the way my 09 is black as well

ghlkal

Here's how the manual describes D+ and D- for my 2011 C300 4Matic

Shift ranges
.
Introduction
.
When the automatic transmission is in position D, it is possible to restrict or derestrict the shift range. The shift range selected is shown in the multifunction display. The automatic transmission shifts only as far as the selected gear.


So, D+ and D- aren't a true manual mode. For example if set to D3, the transmission will automatically be limited to 1st, 2nd, and 3rd gear -- unless you try to over-rev in third, then the tranny will automatically shift up.