4 Bangin, Fuel Sippin, Full Tank Challenge!

Are you guys skipping gears when you drive? going right from second to 4th? and when going down hills are you keeping in in 5th,going into neutral, or downshifting? I always thought leaving it in 5th and using the break was the best for gas mileage. but I could be wrong that's why I am asking. Gas has gone from 3.20 to 3.80 in the last 2 months need to save some cash where I can.

 

i'd bet that staying in 5th or whatever and braking would give better gas mileage. or better yet stick in neutral. but i like to be in the appropriate gear in case the situation arises where i need to boogy

 

I would think the stick in neutral would use more gas with an idle engine since gas is freely flowing into it. Where in 5th gas would me regulated more? Any advise on the shifting does it save gas to skip a gear if you can do it?

 

In neutral my truck idles at about 850 rpm, in 5th at 55 mph it's pulling about 2000 rpm. I have to think that shifting into neutral gives you better fuel economy.

 

On whether to skip gears, it is better to accelerate reasonably quick, but shift at or below 2000rpm going through all the gears. Any time you rev high enough to skip 2 or more gears your way into the 4500+ rpm and that where you're using a lot more fuel.

On coasting in neutral vs staying in gear, it is usually better to coast in neutral.

The obvious time to stay in gear is when going down long grades where you have to brake anyway. 4th or even 3rd might be the right gear to maintain appropriate speed down a mountain.

Decceleration fuel cutoff only happens above 1500rpm which requires downshifting through the gears to maintain zero fuel. If you plan ahead you can coast a long way to the upcoming red light instead of staying on the gas in gear until you can reasonably coast in gear.

Coming of the interstate at 70 toward a stoplight where you have to slow way down anyway is another time to coast in gear.

 

Alexander,
If going down a genuine hill, coast useing 5th gear above 50 MPH, 4th gear between 35 and 50. The truck uses no fuel in this mode as the injectors are shut off. IF just going down a gentle grade I select neutral, as this allows me to take it to the stop light without re-applying the throttle.

When my Ultragauge is below 10 gal of fuel remaining it measures fuel in 1/100 th of a gallon. These new VVT engines with multipoint FI use hardly any fuel at idle. I have sat at 4 minute red lights and the engine does not even use a measurable amount on the gauge.

Two other ways to save appreciable fuel is to coast down any hill. The more you do it the better you get at re-applying the throttle to keep a steady speed.

This next tip really works but should not be done in heavy urban traffic or when you have a f'in tailgater on your a$$. This is when heading up small to moderate grades, hold your throttle steady and let the truck lose a couple of MPH up the grade. The Ultragauge shows 4 to 6 more MPG up a moderate grade at 60 to 70 MPG vs. applying throttle to keep a steady speed up the hill. Get a gauge and you will discover what a fuel waster cruise control is. Up grades mileage will drop down to a indicated 14-16 MPG at least 1/4 of the way up the grade. Driving with a steady throttle up the grade the mileage 95% of the time will not drop below 20, and many time up small grades it hardly drops at all.

So the question is, is all of this worth 2-3 MPG. Depends on how much you drive and what fuel costs are in your area. Its wil be a good thing to know these tricks when fuel hits the next new threshold higher. Which will be $5 to $6 if the general economy improves a lot.

Sorry to ramble on.

 

You're right, if you take your foot off the gas you may deccelerate for a short while using no fuel until your rpm drops to 1500 and then it will kick the injectors back on to keep the engine running at higher fuel use than if you are in neutral, and potentially coasting a long way further with minimal gas.

 

Worthywads,

You mention 1500 RPM as the point when the injectors kick back in. On my truck I can feel them kick in, but it is at 1100 RPM. I wonder if it is a difference in the fuel mapping between your '05 and my '08.

 

That's an approximation. On my scangauge the rpm is I more accurate than the dial gauge. I'll do some further checking and see where it kicks in, just under 1500 is what I remember looking at the stock gauge.

 

Thanks man I appreciate the response, from the posts I think everyone got something out of it. Just to make sure I understand correctly I am going to rephrase this.

I am often going up and down some pretty large hills usually around 1500 to 2000 feet. I love in western new york its a little hilly here. When I go down the hill and I have leaving it in 5th gear and just using the break ( i never touch the gas. Gas is the same as the throttle right?) the rpm is about 1 doing this going about 50-60mph. I then shift into neutral to slow down for the stop sign. According to your first paragraph I have been doing this right. I guess downshifting through the gears to slow down will use a lot of gas and this is why its not mentioned correct?

Now for the second part this is where I got confused just to make sure I understand correctly:

The hills I drive on are pretty steep. So your saying start off in 5th ( I have been doing this) let the MPH drop then shift to 4th and hold in 4th as long as you can until it drops again then shift to 3rd?. I have one hill in mind right now. I start off in 5th about 60mph till the mph drops to about 50 then shift into 4th. 4th will fluctuate between 35-45 depending on the steepness of the hill ( its has different grades in different spots)Sometimes I will need 3rd depending on what side of the hill I am coming up. So Just start off in the highest gear then just downshift as needed? I can do 55-60 up the hill but thats in 3rd and the rpm is about 4200 I would imagine that is just sucking gas. So I try to use the 4th to save gas. am I way off here?

 

Alexander,

In your situation with really steep grades both up and down I find 4th to be a better solution than 5th. The key is to find the optimum time at the bottom of the hill to re-apply the throttle(gas) to get up the hill with a minimum amount of throttle pressure. I tend to reapply the throttle about a second before the bottom of the hill, in essence giving the truck some momentum before heading up the hill. And the second key to is to make sure you coast down the hill in gear to shut off the injectors.

When I vacation in the Ozark Mtns of NW Arkansas I find the hilly roads can yield really good MPG numbers when driven in this manner. In fact my old Honda Accord got it best MPG ever driving like this in the hills. And if the funds permit get a Ultragauge(about $80-$90) or similar, it will make you a better hypermiler, no matter to what degree you wish to take it. Any fuel I can save, and not send that money to the oil & corn ethanol barons both foreign and domestic makes me happy.

 

Further check found mixed results. In 2nd and 3rd it seem obvious that it kicked back in around 1200-1250.

4th and 5th were not as obvious but the scangauge was showing as low as 975 before it went back into open loop which. Not really an rpm you want to be in 4th or 5th. Maybe there is more opportunity to keep it in gear at lower rpm than I thought.

 

I have a question for you MPG gurus. When going up a steep incline on the interstate (70mph), is it better to stay in 5th and give it more gas, or is it better to down shift? If I stay in 5th gear, I'll creep down to nearly 55mph by the time I hit the top of the hill. If I down shift, I typically have a lighter foot and I can keep it above 65mph.

So, my main question is is it better to stay at higher RPMs but less throttle, or more throttle at lower RPMs?

 

Staying in 5th and slowing to 55 will net you better mpg than downshifting and keeping it to 65. Downshifting and slowing to 55 would use more than staying in 5th too.

 

JoshM

When you head up the incline at 70 and end up at 55 MPH, is the throttle fully depressed. If that is the case a down shift would probably be beneficial. If at 1/2 throttle or so, 5th would be preferable. The key is to keep steady pressure on the gas pedal.

The best MPG would be to hold the throttle steady at the bottom of the hill, and let the vehicle lose speed up the grade. As I mentioned in a previous post, this method will show 4 to 6 more MPH on my Ultragauge, up the grade than trying to remain at 70 all the way up the hill.

Happy experimenting

 

170 miles when I got home from work today... gauge showing about 5/8.

 

Well this has been a very productive thread!! Thank you everybody for helping me out.

 

Thanks!

When I stay in 5th gear, I keep the throttle around 30-35% (according to ScanGauge).

 

I plan to reconfirm some tests I did in the past, but did try again briefly on a small but steep hill on the way to work this morning.

At 50 and 5th full throttle I was showing 19-20mpg and then shifted to 4th and held 50 and it dropped to 16-17.

It seems 5th is better for me even at full throttle.

 

If I did that my Ultragauge would show 12-14 MPG all the way up the hilll. It will show 17-18 in 4th if I maintain the speed I started up the hill with. Probably just the difference in the algorithm used in programming the fuel use, relative to speed and throttle position. Its a shame that the OBDII connector does not receive fuel use info from the ECU, that would make the gauges even more effective.