MVPlaya

I was reading a post where someone was getting good gas mileage.

They said they shift gears quick, and basically let 5th gear climb on its own.

Does this actually save gas? When I shift early, I always feel like the engine is working harder when you let the hears climb.

chaseonbass

that sounds rather unintelligent.

sciondrgn

+1

More then likely the engine will have to work more to catch up to the gear and in turn waste more gas.

Stay within the gears RPM's and drive normally will more then likely yeild you the best mileage.

GarmaZed

Yep, this puts too much stress on the engine. Have you ever ridden a mountain bike before? Imagine putting it in the highest gear and trying to pedal from a start... pretty much impossible, right? That's what it's like for the car. There's a list that Toyota recommends for when to upshift and downshift, fortunately somebody just posted it elsewhere, so I can post it here.

Menace

He is actually right to a certain extent. You can hit 5th at 35mph for instance and have it gradually climb to your desired speed. Those speeds posted are a balance between performance and economy. As long as you don't make your engine knock you can upshift to improve economy. You will however have no power at your disposal, especially in 5th in case you may need to accelerate. Going WOT or even pressing the gas harder than your car is able to accelerate at 1.5RPMs is also to be avoided.

Ace83

iTrader: (6)

Yup but to make things simple use the tach meter when shifting. Shifting at low rmps saves you gas but too low will not.

Deathwish238

If I'm in an economical mood I'll shift at 2.5k. If I'm in a normal mood I shift at 3k. If I don't care...I shift before 5k


What are the best shift points for strictly performance?

Ace83

iTrader: (6)

performance, you mean like racing? i guess before the redline?

forpinks

That is crazy... I get 31MPG using my 4th gear when climbing hills at 80 when I'm breaking in my tC.

So 5th gear has to make your engine work so much harder to go to a certain speed than the gear that speed is supposed to be on. (REMEMBER, 5th gear is OD!)

Lets say the car is going 35 MPH, and you use 5th gear, it's like the same consumption of fuel as in redlining 2nd gear. (You should always keep your RPM at 3-4K RPM and your tires at 35PSI to get best mileage.)

Ace83

iTrader: (6)

5th makes your engine work harder if your speed is too low for that gear and this goes like with any other gear like 3rd or 4th

FREEradical

It's really not the engine that gets "stressed" If the engine is feeling stressed it'll just stall. What takes the wear from using too high of a gear is your clutch. Drive around shifting gears too early for too long, and your clutch is taking excessive wear from not being matched up w/ the engine speed properly.

djct_watt

OD should be used to maintain speed, not gain, unless you are at VERY high speeds. Also, don't forget that excessively low RPM's in gear puts A LOT of stress on the gears' teeth. Expect slipping hears in the future...

Menace

Umm, the higher, the more power to the wheels.

Completely inaccurate. Like stated above, your engine speed has nothing to do with the actual speed. If you are in 2nd almost redlining you are wasting a LOT of gas. There is a direct correlation between RPM, Power(99% of the time as there are weird power band curves), and fuel consumption. The faster your engine is working, the more fuel you are wasting, and the more power you are exerting on your flywheel(once again in most cases). Gears are just multipliers that transfer power to the wheels. If you are at 1.5k RPMs in 5th trying to make it up the hill, you will stall. There is not enough power going to the wheels. The reason you drop to 4th or even 3rd is to drop to a power band that has more power, but in turn you waste more gas. Early upshifting is economical driving. If you don't knock, you are fine in that particular gear and consuming less gas than if you would be going same speed in a lower gear.

djct_watt

^you're off too, buddy.

Yes there is a correlation between engine speed and power, but it is proportional to how much you are pushing the gas pedal down. Fuel consumption at high RPM's but in vacuum (no throttle) is marginal at best.

Most of you guys really pretend to be experts here, and i'm no expert either. But there are more variables than just speed and RPM here, ie load, acceleration rate, throttle. There really is no cookie cutter formula for maximum efficiency. There is an optimal balance yes, but the key idea is not to drop the RPM too low or too high.

Your best bet for optimizing MPG is to maintain a constant average speed, which means you won't be shifting at all and/or decelerating. Use the highest gear possible (without making the engine struggle) yo MAINTAIN speed. Please note that maintaining speed and gaining speed are completely different matters.

Menace

You are incorrect your self. There is NO fuel consumption without throttle. I skipped it above because I covered it earlier. Maybe I wasn't clear, but it was implied that when the gas pedal is pressed in 2nd gear AND your speed is constant, if you are near the redline, then you are wasting more gas than if you were to be driving the same speed in a higher gear. There are a lot of variables, yes, but covering load, acceleration, etc will not have a benifit on either side of the argument. I can also cover, lighter flywheel, difference in octane's effect, rev matching properly, etc but I put it in as much layman's terms as possible so everyone has a general idea.

djct_watt

The problem isn't my accuracy, it's that you aren't reading what I wrote. If you had done that you'd realize that I was saying EXACTLY that. Fuel consumption at zero throttle is negligible (meaning near zero). Throttle input is not off and on; there is an infinite combination at any given time, meaning partial throttle. Now if you are cruising, you want the highest gear possible (which is in 100% agreement with what you said). However, AS I PREVIOUSLY SAID, it is a completely different matter if you are accelerating or under load. It is not fuel efficient to go up a steep grade at 100% throttle at 20 mph in 5th gear, nor is it efficient to redline up the hill.

Menace

Have you read the entire thread? I already covered that as well. I address post by post, if my every reply was an addition to what I previously said then my last comment would be 2 pages.

SoccerBoy_AP

Well I would assume 5th max is 128mph or w/e our rev limiter imposes on the engine

superemu

menace is correct on this guys...

quiksilver24r

I don't have the tC anymore, but I figured my two cents maybe worth something... I figured it out. I used to shift at 2500 assuming it gave better gas mileage. But with how the gear ratios are setup, it makes the engine work much harder to get up to speed than to just ride out those extra 500 rpms. For optimal fuel economy, shift at 3000. And it's not too boring that way too.