Coasting for better mileage?

You should honk when you see that haha funny to see them freak out thinking they missed the green.

 

Thanks this is great info. Learned something new regarding coasting in gear vs in neutral!

 

Old thread revival. I almost can’t believe the fuel mileage I got out of my truck this week. 26.42 mpg hand calculated. 2012 Regular Cab, 2.7l, 4x4, automatic transmission, AC Off, with cab height camper shell. 80% driving 55mph on 55mph roads, 20 mile trips mostly.

 

Attack of the necrothread! Holy revival Batman! I get 22-24 MPG with 50% city driving, so your numbers sound about right.

 

When I took my road test for my class A CDL, the truck must be in a gear whenever the brakes are released. Even waiting at red lights. You must sit there holding down the clutch pedal. Kind of tells you something about the coasting.

 

You have to keep it in gear and not coast because the tractors uses a non-synchronous transmission. It is a form of transmission based on gears that do not use synchronizing mechanisms. Your engine speed needs to match your road speed or it won’t go into gear. That’s why you don’t shift going up or down an incline. If you try, you can end up with a new gear called “Georgia Overdrive” aka Freewheeling. The next thing to come is burned up brakes followed by a crash or a roll.

 

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Thanks. They never mention about that. The tractor I trained on had 6 speed synchronized transmission. Still I feel that coasting is a bad idea and I may be wrong but don't fuel injected vehicles shut off the injectors when your foot is off the gas and still moving?

 

I don't know about diesels or tractors. But if you are talking about modern passenger vehicles or light trucks with gasoline fuel-injected engines, yes the vast majority will turn off the injectors when the computer sees the conditions are: at or near full temperature, 0% throttle, RPM above ~1200. (No fuel below those revs could lead to a stall or other problems, I suppose.) This is called deceleration fuel cutoff (DFCO) and is intended for fuel economy. My Corvette and Tacoma both have it, and the compression braking with no fuel input is very noticeable. Used properly, it can also prolong the life of your brake pads and shoes

 

With some of the previous manual trans cars and trucks I've had, I would usually throw it in neutral and coast up to a stop sign or traffic light. On downhill sections where I knew it would maintain the speed limit I would coast as far as I could before putting it back in gear or coming to at stop. It definitely increases gas mileage since you're rolling quite a distance at idle speed. With my current 2013 Tacoma with the A4, I know it will go into overdrive at 35 mph so if I'm on a flat road or a downhill, I use overdrive and when I know I'm coming to a stop sign or traffic light that is always red, if nobody is on my bumper, I will coast in OD until I reach the stop. My last tank fill up came out to almost 18 mpg with 305/65/17 (33") tires, towing the boat multiple times and no highway driving(all less than 50 mph). When I start to coast while coming to a stop, you can see the mpg go up on the scangauge.

 

Times and places for both, some grades are insufficient for coasting in gear so you have to ride the skinny pedal anyway, some slight grades are just right so that you can hit the timed lights and coast in neutral practically all the way to the freeway, while others require engine braking. I'm curious about whether idle coasting or in gear with just enough skinny to maintain speed is more efficient since both require fuel flow. I'll shut off the engine if I just miss the green at a 4-way with long lights but some of those can be sidestepped by taking a side street. Mileage involves simply another skill set that takes willingness and practice balanced by prudence. "It's a truck, who cares?", is a mindset, every single vehicle made can do better or worse depending on how it's driven but hypermiling a truck seems a lot less incongruous than hypermiling a Porsche.

 

I've been driving for 20 years. I don't pay any attention to how "they" tell me drive. "They" are idiots who have never driven a semi and if they ever did they forgot everything. I coast with the clutch pedal in around every corner. At least back before they went to the useless, dangerous automatics. I've been driving for 44 years and have never had an accident. These idiots at the trucking companies know nothing. It's their lawyers they bow down to.

 

The Grandfather of a high school friend of mine used to turn off his Ford Ranger every time he was coasting down one of the hills over here in Central East Texas. He’d be driving at about 55mph, get to the top of a hill and put the shifter into nuetral, turn the truck off, and wouldn’t turn it back on until he began to bleed-off speed ascending the next uphill stretch.

He did it like it wasn’t no thang.

 

Every vehicle has a sweet spot...you will save far more fuel driving more slowly on the highway. A certain amount of energy is needed to overcome the distance, altitude and resistance, you can not change the distance nor altitude, but you can change the resistance...as you are attempting with the coast...it takes less energy to accelerate down hill and in the trough...some vehicles coast well and have a higher sweet spot of resistance, so it may make sense to increase speed to the upper end of the sweet spot on the down hill and coast up hill until you reach the lower end. Of course you will get rear ended by tractor trailers and SUVs but you may eek out a KPG once in a while. The "coast" algorithm therefore can help as long as you stay within the resistance sweet spot standard deviations. Good luck.

https://www.toyota.com/car-tips/fuel-efficient-driving-techniques-that-work