I just bought an '04 TL (auto) and I am guessing I will get less gas mileage if I manually shift rather than keep it in drive. Gas mileage is 20 city 28 hwy if I keep it in drive. How much do you think it would be if I manually shifted?

 

well, it all depends how you drive. if you shift often and keep the revs low then you may get better, but if you redline every gear then you will get worse. but the same holds true for manuals too. my guess is the computer will shift "better" than you so overall you will probably get a lower mpg.

 

The computer looks at the throttle input and uses minimum revs to get to top gear.
All the smog controls working together do some complex reckonin and make decisions.

Human pushes pedal hard, and will shift 500- 1000 rpm higher per gear- and forget to go into 5th on the freeway for that last 500 rpm savings.

 

Hint: SS stands for Sport Shift

 

These are my observations with a 07 TL...
These observations are based on driving about as conservatively as possible on releatively flat roads.
In my city driving, the fully automatic mode keeps the vehicle in a lower gear for a longer period of time compared to sport shifting; especially the highest gear.
Using SS, high gear can be achieved at about 39 mph as compared to about 45 mph.
4th gear can be SS'ed at about 20 mph.
Of course, don't expect to accelerate quickly at these low speeds in those higher gears.

If lower rpm equates to better fuel mileage then one would expect better milage using SS.

Then there's the brakes...using the highest possible gear with SS will allow you to coast further; at the expense of your brakes

 

I've never shifted to ss to save gas, only to waste gas

 

can you elaborate on that, please? maybe it's just me and because it's Monday, but i'm not understanding the expense of the brakes part...and am curious because i think mine will need to be replaced soon...


also to the OP, from my experience, i drive 99% in SS and have noticed it all depends on your driving...i like SS mode because you control where your revs are, so i usually shift between 2300-2700 rpm, which is slightly lower sometimes than the car shifting itself...now of course if you let the revs climb before shifting, letting VTEC kick in and all, then expect lower MPG, especially with a CAI...

FYI: when i drive conservatively in SS, i get 24 MPG mostly city driving...if i drive my normal way (somewhat aggressive), i get 21-22 MPG mostly city driving...i've also got an '04 Auto, but with a CAI installed...

 

Given that you can shift and have your RPMs at a lower number as versus to automatically shifting.. it should be higher, if I'm not mistakened.
But the whole point to driving auto is if
a) you don't know how to drive a stick-shift
b) you don't want to deal with a stick-shift
but with paddle shifters or that sequential-gear-box [pushing the lever up/down or left/right] sure adds some fun into auto cars..

 

In SS mode the car will not automatically down shift as early as in full automatic mode.
the 5th to 4th downshif in SS mode happens at approx. 39 mph,
the 4th to 3rd down shift happens at approx 20 mph.
You have less engine braking going on.

 

ooooh...thank you for clearing that up for me...

 

here u go manual shifting = more of a beating / letting the computer do it all for u = less of a beating. which do u think wastes more or less gas?

 

[I have made numerous observations of gas mileage, and what it really comes down to is at low speeds / city driving, gas mileage drops hard- regardless of little "shift point" differences.]

In automatic mode, the engine is designed to upshift and downshift based upon certain criteria...obviously

If you use SS and shift more conservatively then you should be saving a bit (My experience is its very negligible). Vice versa, if you use SS and shift at higher RPMs you are going to probably lose a bit.

Here is my opinion though: the automatic mode does not seem to do a good job judging gears when slowing to corner. When I want to be in 2nd coming out, it will stay downshifted to third. This type of gear efficiency is one of the reasons why people prefer manuals. You pick the right gear for the job - sometimes the job is to be conservative, sometimes its to be aggressive.

Moreover, people drive manuals for the feeling of control. When I want to make a pass of someone on the freeway for example, I prefer to anticipate my moment and downshift manually, rather than stomping on my gas to make my car "realize" that is what I want to do. It has complex computers, but those computers first have to think "This guy is giving me a lot of gas, maybe I should just downshift." Why does it need to do that when I already knew that?

Final thoughts: Driving in sports shift mode is more fun and provides those of us who bought an automatic (for better or worse) some excursion. I certainly don't mind leaving in automatic though when I'm in mind numbing traffic...

 

my thoughts exactly...when i drive in auto mode, i find myself accidentally gassing it too hard sometimes just trying to pick up speed slowly, but it's really the car thinking(?) i want to floor it...and vice versa...when i want to get going, being able to choose my own gear is much better than letting the car determine where i need to be and flooring it for me...