Is this normal?

[LostSouthernStar]

Hi everyone,


First off, let me say that everything on my Camry is mechanically sound and up to par, tires inflated at sidewall pressure, suspension is fine, engine and transmission are working very well, no excess weight in my car nor aerodynamic drag and I am not using my air conditioning as it is winter here.



Here is where my confusion begins...


I have been testing my fuel economy since spring 2011 and have always been averaging 33-36 mpg. I've followed every SAFE and USEABLE fuel economy driving tip known to reach this milestone.

There is one concern that I have and I wonder if it is how this generation of Camry was designed, if it is just physics or if it is me....but when I accelerate from a stop, I try to keep it at 2,000 RPMs or less as recommended for better fuel economy...usually reaching 450-500 miles on 1 tank as compared to accelerating to 2,000-3,000 RPMs and reach only slightly less...about 1-2 mpg less or 375-425 miles on 1 tank...depending on if I drive elsewhere other then my commute route which is 90% highway.

Nothing is wrong with my car, I am just curious what is the best RPM range to achieve the best fuel economy. If its too low, it will bog down and if it too high, it will damper fuel economy.


WHY am I not getting near the same results each fillup???


I know the Toyota Camry was not built for fuel economy champion but I would like to be able to get the most out of it that I can.




I sure would appreciate your input and any theories you may have.



Thanks!
-LSS

[ghettosled]

im my experience, keeping the RPMs low is a must for better fuel economy. drafting on the highway helps and so does taking advantage of rolling hills (i dont know if there are too many in texas, lol). another thing i do which im sure many people frown upon for being not too safe (but i think its okay) is i run my tires at 50psi. less rolling resistance, but watch out for potholes as there is a greater chance of damaging the tire.

fuel economy will always vary because of a number of variables. daily temperature, wind, having to accelerate from a stop couple more times than the previous fill-up,

[LostSouthernStar]

I agree with that...but how low is low for RPMs?


To take advantage of rolling hills, is it better and easier on the car to coast in drive or neutral?


I have my tires inflated to maximum sidewall pressure at 44 Psi.

Originally Posted by ghettosled

im my experience, keeping the RPMs low is a must for better fuel economy. drafting on the highway helps and so does taking advantage of rolling hills (i dont know if there are too many in texas, lol). another thing i do which im sure many people frown upon for being not too safe (but i think its okay) is i run my tires at 50psi. less rolling resistance, but watch out for potholes as there is a greater chance of damaging the tire.

fuel economy will always vary because of a number of variables. daily temperature, wind, having to accelerate from a stop couple more times than the previous fill-up,

[Chris Crash]

You've got an automatic, so let your ECU worry about the RPM's and just keep cruising at whatever pace you're doing well at. As far as rolling in neutral, I would advise you not to do so in your automatic transmission. Rolling in neutral you do not get the same lubrication through your transmission as you would if you were in drive, so it's more likely to overheat and damage your transmission.. This is why most people remove their drive axles when pulling their car behind their RV (..or they should!).

For a manual, however, it becomes more of an issue. Sometimes, lower RPM's aren't always good. Going 40 mph in 5th gear up a hill you might be doing 1200 RPM but you're wasting a lotttttt more fuel than if you downshifted to 4th or even 3rd. The harder the engine has to work, the more fuel you consume. The largest problem I've been having is finding that sweet spot...knowing when it's appropriate to downshift and let the RPM's rise up or when I should stay in the higher gear.

[calnra]

As far as I remember the 5s-fe's torque curve is pretty flat after 2000 RPM, so I keep my rpm under 2500(70mph in the gen 4s puts the engine at 2500 RPM or so).

Didn't you start a couple of Ultra gauge threads? If you commute the same routes, why don't you just look at how the ultra gauge says you are doing depending on how your right foot is pressing the gas pedal? The differences should be easy to spot on the same route and conditions.

[LostSouthernStar]

Thank you so much!


So accelerate lightly or average? Then let my ECU worry about RPMs that way?...


What about idling at a light in neutral? Wouldn't the force of the engine and transmission wanting to move forward while having the brakes hold the vehicle back cause more strain and fuel loss versus shifting to Neutral and releasing the brake if on flat terrain???



I notice the shifting is most odd between 40 and 50 mph because its between 4th and 5th gears trying to find the sweet spot.




Thanks!

Originally Posted by Chris Crash

You've got an automatic, so let your ECU worry about the RPM's and just keep cruising at whatever pace you're doing well at. As far as rolling in neutral, I would advise you not to do so in your automatic transmission. Rolling in neutral you do not get the same lubrication through your transmission as you would if you were in drive, so it's more likely to overheat and damage your transmission.. This is why most people remove their drive axles when pulling their car behind their RV (..or they should!).

For a manual, however, it becomes more of an issue. Sometimes, lower RPM's aren't always good. Going 40 mph in 5th gear up a hill you might be doing 1200 RPM but you're wasting a lotttttt more fuel than if you downshifted to 4th or even 3rd. The harder the engine has to work, the more fuel you consume. The largest problem I've been having is finding that sweet spot...knowing when it's appropriate to downshift and let the RPM's rise up or when I should stay in the higher gear.

[Chris Crash]

I've heard conflicting ideas;

Accelerate lightly and take your time getting up to speed, keeping RPM's low, thus saving fuel.

OR

Accelerate quickly and get up to speed quickly (and safely) so less time and allegedly fuel is spent getting there.

I don't have a say on either of those, that's up to you.

As far as at stop lights, if it's a long stop light, go ahead and shift into neutral. I have heard it helps, but I'm sure it's very very marginal if at all. However, remember to shift back into drive when the light turns green! I've had a few ocassions where people approach a red light, pass the line so they back up (thus getting really, really close to me) and then stay in reverse. Luckily I noticed both times they were still in reverse, so I backed up myself because I knew they obviously had no idea. Sure enough, the light turns green and they floor it..........in reverse. Then slam on the brakes and shift and floor it again.

[LostSouthernStar]

Those were 2 theories I have heard as well.


I know 55 mph is the generic sweet spot for most vehicles but is it the sweet spot for a 1997-2001 Camry? I know every car is designed differently with different specs, etc.


I will test both theories with my ultragauge and see which is better for fuel economy.


Ok, then I will just leave it in drive if it doesn't really help...I was more concerned about more wear on the transmission.



Thanks!

Originally Posted by Chris Crash

I've heard conflicting ideas;

Accelerate lightly and take your time getting up to speed, keeping RPM's low, thus saving fuel.

OR

Accelerate quickly and get up to speed quickly (and safely) so less time and allegedly fuel is spent getting there.

I don't have a say on either of those, that's up to you.

As far as at stop lights, if it's a long stop light, go ahead and shift into neutral. I have heard it helps, but I'm sure it's very very marginal if at all. However, remember to shift back into drive when the light turns green! I've had a few ocassions where people approach a red light, pass the line so they back up (thus getting really, really close to me) and then stay in reverse. Luckily I noticed both times they were still in reverse, so I backed up myself because I knew they obviously had no idea. Sure enough, the light turns green and they floor it..........in reverse. Then slam on the brakes and shift and floor it again.

[LostSouthernStar]

Thank you for your reply!


That's for top speed, what about acceleration from a stop and while moving from a slower speed to a faster speed???


I still haven't setup my ultragauge. I need to make time to install it.


Thanks!

Originally Posted by calnra

As far as I remember the 5s-fe's torque curve is pretty flat after 2000 RPM, so I keep my rpm under 2500(70mph in the gen 4s puts the engine at 2500 RPM or so).

Didn't you start a couple of Ultra gauge threads? If you commute the same routes, why don't you just look at how the ultra gauge says you are doing depending on how your right foot is pressing the gas pedal? The differences should be easy to spot on the same route and conditions.

[calnra]

Originally Posted by LostSouthernStar

That's for top speed, what about acceleration from a stop and while moving from a slower speed to a faster speed???

I've had mixed results. I did find that if I used too little throttle then the car struggles just to maintain speed and end up burning gas without much progress.

What I end up doing now, from a stand still, is to use just enough throttle to let the car work up to 2000 RPM, and ease up on the throttle to trick car into an upshift into the next gear. Rinse and repeat until it gets into the highest gear it can stay without needing a downshift due to bogging. You will know when the car is bogging.

I still haven't setup my ultragauge. I need to make time to install it.

The BIGGEST contribution of my ScanGauge e is its instantaneous mpg readout that helps me to back off my throttle input when my right foot gets too enthusiastic. You want to use the minimal amount of throttle to maintain the speed you want to stay or reach.

The suggestion above of taking advantage of rolling hills is a huge help. Give up a little ego and stay in the right lane, and when you have enough space between you and the car behind you, keep a constant throttle pressue while letting the car slow down a little saves you a LOT of gas. Then let the back side of the hill help you to reach a crusing speed. In urban areas with lots of overpasses, this helps quite a bit.

Getting 33-36mpg in the Gen 4 is pretty good as it is. The only better way to drive them might be to find a route with 40-50mph speed limit and minimal amount of traffic lights. It constantly surprises me how efficient our cars are at that speed range.

My commute has a lot of congestion and I found just by leaving a small space cushion in front me, I can stay off the throttle and let the car "pulse and glide" with the traffic pattern. I've gotten my BEST milleage in moderately heavy traffic that doesn't flow slower than 20mph and over 45 mph. (note: I do not shift into neutral for the glide part))

By all means get your Ultragauge set up and find out how your situation works. Just lots of repetition and find what works best for you, and do so safely, of course.

[calnra]

Originally Posted by LostSouthernStar

I know 55 mph is the generic sweet spot for most vehicles but is it the sweet spot for a 1997-2001 Camry? I know every car is designed differently with different specs, etc.

I am by no means an expert in this area so this is pure amateur guessing.

This is a pretty common pattern for the torque curve for the 5s-FE engine:

http://www.6gc.net/forums/index.php?showtopic=55606

Granted it's from people working with Celicas but it's the same engine, more or less.

note that the torque is well above 100 ft/lb at a lowly 2000 rpm. It only goes up another 25% or so at 4100 RPM.

since the 5S-fe with a 4 speed A140E turns at 2500 RPM at 70, that gives about 56 mph for 2000 RPM. I have not seen any data for torque at under 2000 RPM so I need to find a way to test that without getting run over on highways. But 55 should be a very efficient speed for the 4 speed auto with the I-4.

Hope this makes some sense to other people.

[LostSouthernStar]

Thank you!

The speed limit on the highway I drive is 70 MPH and its only 10 miles to my work on the highway itself. I only have 3 stop signs to pass through when leaving my home, but theyre pretty spaced apart. Then only 2 stop lights right next to my work.


I drive 55 and stay in the right lane, though I am constantly passed by other drivers. There is another route I can take where the speed limit is 55 but its about 3 miles longer and it has
5 stop lights, spaced out a good ways from eachother but they sneak up on me and I can never tell when they're going to change unlike other stop lights...then I go through 3 stop signs spread out between these lights. So there is more stopping involved but the speed limit and traffic flow is much lower...so I have no idea which would be more efficient.


I have always stuck with the highway route with the least amount of stops and stayed at a low speed in top gear.



It seems the Gen 4 kicks into top gear between 47-50 mph, depending on the incline. I have done the trick downshift as you described and found it works quite well.


I am curious to test all of these tricks with my ultra gauge to see how well they really work, that will be the only way to tell. My goal is travel at least 500 miles on every tank...so far the best I have done is 440-450 miles with 1/4 tank remaining...then again I cannot really trust that gasoline gauge as it has been wrong numerous times.

[ghettosled]

on a note about shifting into neutral when at a stop - my dad does this all of the time and every car he drives needs the transmission rebuilt at about 100-120k miles. i dont know if that is bad luck on his part, but ive been told my mechanic friends NOT to do that because the most strain a transmission sees is shifting into gear. once it's in drive, leave it there until you park.

[LostSouthernStar]

Thank you so much!


I'll take a page from your dad's book and just leave it in drive. It would be different if it were a manual transmission.



Thanks again!

Originally Posted by ghettosled

on a note about shifting into neutral when at a stop - my dad does this all of the time and every car he drives needs the transmission rebuilt at about 100-120k miles. i dont know if that is bad luck on his part, but ive been told my mechanic friends NOT to do that because the most strain a transmission sees is shifting into gear. once it's in drive, leave it there until you park.

[nelbur]

....tires inflated at sidewall pressure,

What? That pressure on the sidewall is a max pressure for cold tires, as in a do not exceed pressure. The proper pressure is listed somewhere on your car, and while high tire pressures will help gas mileage, it will lengthen stopping distances and reduce your ability to control the car in emergency situations. In my opinion safety trumps economy. Look for the proper tire pressures and enjoy the improved ride they will give.