When To Shift Gears For The Best Fuel Economy

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Engineering Explained : Here are two additional videos which supplement this nicely, hope everyone's having a great day! When To Shift For The Best Acceleration - https://youtu.be/zZBqb0ZJSwU LSPI: Don't Lug Your Engine - https://youtu.be/soJea7xEt-8

Stewart Mckinna : The best time to shift gears is when your right foot is touching the firewall and the rpm needle is sword fighting in the hotzone

NDash On Cars : In a nutshell: *As soon as you can without bogging*

Daniel G : If you live with LA traffic and drive manual, you are already obsessive about this subject.

Seth : High load low rpm = Miles per gallon High load high rpm = Smiles per gallon

Frouch Itude : For the best fuel economy, walking is pretty efficient.

protoslashwyl : really liked the 4 split screen with added graphics

Ben Goyette : the red dude at 6:34 had pretty good fuel efficiency

Darzy : When you own an s2000 its 9k every gear!

Ashwin Mohan : Many petrolheads I know and I'm one of them, do like to do economy driving. We have a simple system where we try to get into higher gears ASAP and keep the rpm below 3000 WITHOUT lugging the engine. I have a Honda City, which can be quite comfortable even below 2000. Infact, what we are doing is exactly what Jason says. Load it as fast as we can and keep rpm low, and NEVER ever brake (unless you relly need to, cause braking is waste of fuel). Try to coast near red lights and crossings. Blasting through highways and backroads is fun when you got loads of fuel, but can get real interesting when you are low and filling stations are far. Jason explained it engineeringly, ofcourse!! Thank you for another great video.

Cars Simplified : I kind of always figured this was the case, but it is very cool to see the details behind it and an actual test!

Mikael Abrahamsson : In "ecodriving" courses, it's taught that in constant speed, use the highest gear where the engine runs well (not lugging). This is consistent with your advice. Now, another interesting question is what to do when you're at a stop light at standstill, and you're going to accelerate up to let's say 70-100km/h. Then the advice is actually to accelerate fairly hard to get up to speed quickly, so that you then can use higher gear for longer distance. You didn't touch on this at much (actually the title of this video would better have been "what gear to choose when driving at constant speed"), but I think it's an important topic. Some people think it's fuel efficient to slowly accelerate, but this just keeps them longer in lower gears which is not efficient. So the advice for best fuel economy is to put in quite a lot of throttle (probably in the 1500-3000rpm band you were talking about) to get yourself up to desired speed, and then choose the highest gear suitable for that speed. Then another thing for fuel economy is to avoid using the brakes. So coasting is important, if you see well ahead that you're going to have to reduce speed, get off the throttle early, and coast in gear. On petrol engines, this cuts off the fuel supply completely, so as you're coasting, you're using no fuel. This means from highway speeds you can get approximately a kilometer of "no-fuel-used". I see way too often people maintaining speed almost up until the stop light or whatever, and then get on the brakes. https://en.wikipedia.org/wiki/Energy-efficient_driving has lots of these things.

Imrahil : You kinda ignore something important here. Throttle setting during acceleration. You're actually using up most of your fuel accelerating, and here's where I see most people screw up. For some reason people think gentle acceleration makes for high fuel economy. Starving the engine of fuel never allowing it to get to peak efficiency...

Frouch Itude : When you see the smoke, it is time.

Yathu prem : 2:48 How can you do that. Talking that complicated while driving

Monster RAM : No first gear at 60mph? 😜

AD1 : Your test is kind of incomplete because you tested the coasting efficiency of each gear but didn't test the differences of efficiency to reach that speed under acceleration. If the goal is to reach a certain speed, it may be more efficient to do it quickly with less duration of load rather than slowly while being under throttle for a longer amount of time. I'd really like to know where the balance is.

Jerry Fang : I usually shift below 3k rpm on a normal driving.

Resolute Lane : Lol your car in 2nd gear gets better fuel economy than my truck gets in 5th gear

Mojmír Křížek : You mentioning BSFC few videos back changed my driving style and lowered my fuel consumption some 10% more (now reaching 50mpg with 2003 3-cyl 40kw 1.2 liter gasoline). Thank you for that. While you are at it, you should mention pulse and glide driving style that is closely connected with BSFC. You need to know and understand BSFC to understand PnG. I am really happy you care about fuel economy among other things.

MrTehnoGuy : The best time to shift gears is at redline.

Hal 1000 : Finally someone to answer this question. I’ve been debating this with a friend of mine for over 20 years about this. He insists that keeping the rpm as low as possible is better efficiency I always said shifting at the peak torque point is better regardless where that is in the rpm will be more efficient. Looks like i owns him a Coke

Phil Atkins : Basically be gentle and ride the torque :)

arturosporting : Correct me if I'm wrong, but don't you take the best of every fuel drop when the engine is working at it's higher torque zone? I mean, if you are in an uphill, won't you be taking better advantage of the fuel used with the engine working at it's optimum torque zone than with it working at low rpms meaning that it is not working at it's optimum point? Thanks!

craggy rocks : you didn't test it while accelerating though your test was on a constant speed who will use high RPM on a constant speed with all due respect

Johnny Yu : Best time to shift gear for fuel economy ? No problem ! CVT life bro

James Banks : In a turbo engine I get a bit better gas mileage if I stay in a lower gear and not use turbo boost (air fuel mixture gets way richer once you start to lug the engine at all). So if I go up a hill in 6th I get worse gas then if I stayed at higher rpm in 4th or 5th and just stay light with the throttle

Cyril Matthew : I don't have words to express my sincere gratitude for you bro .... Thanks a lot for spreading awareness....

Reee Eee : As early as possible? OK starts from 6th gear!

crazyjr : While i agree with you, there needs to be a caveat. Different engines have different power bands, Straying away from said power band too much, can ruin your mileage. I used to have a Mazda B2200 truck, 2.2 liter 5 speed, it liked to rev and averaged 25 MPG running in the 3,000-5,000 RPM power band, for acceleration. I sold that truck to my dad and he lugged it everywhere and only averaged like 18. asked me how i was hitting 25? I told him to treat it like a bike, rev it and let it run. He tossed me the keys and said, show me how you drove it. When i did, he was amazed it even got mileage, but he replicated my driving style and it instantly got 25 MPG all day every day till he got rid of it. You are right to a point, but the engine has a specific area it likes to and was designed for. if you stray too far outside that comfort zone it can hurt you both in mileage and also durability, because Spark knock is no joke, it'll ruin your engine bearings.

RcFrenzy : Before VTEC kicks in! Seriously though, if I hit vtec at all in my GSR, the fuel mileage would drastically decrease.

DebieDoesDalas69 : My Prius is automatic tho

Gabor Szabo : It is written in the manual of my car, at what rpm should I shift to be fuel efficient. It actually translates into "as early as possible", as Jason said.

CivicChina : modern small turbo engines thanks to higher torque at low rpm allow early shifts, which translates in amazing efficiency if you know how to drive. I can run under 1500 rpm all the time if i really want.

Matt P : I have never been so early to an EE video before! Yippee!

Jason S : Thanks. There will still be arguments about this topic. Why? Because... people.

Fred Smartt : Rev it until the valves float. 😁

Mohammad Fletcher : I don't even have a car, but I've watched as much of your explanatory videos as I could! really interesting stuff! thanks!

Erik Haugan Aasland : I have a question that is perfect for Engineering Explained: Is it more economical to to a reasonably fast acceleration to the desired cruise speed or is it better to do it slower? The variables are interesting - the time spent accelerating being the one that springs to mind first. Hope you can make a video on this, if you haven't already. Great channel, by the way - I learn so many interesting things! :-)

Casey Stoner : When Vtec kicks in yo.

rarbi.art : "shift up as early as possible": off course. But my question is always: how to safely determine what is "too low". I really like to roll near idle speed. How to determine when a (bigger) engine is suffering from low RPM? (below idle it's gonna starting to jump, that's clear.)

KINGatLIFE : So basically do what you already do without revving to high. Oh and coast in 5th when going down hill.

Top40Bill : Overcoming gravity is not a resistive force. It is a transfer of energy from the engine into potential energy (weight x height). When you go back down the hill, the potential energy is used to reduce or overcome the resistive forces. Only the energy that is used to overcome resistive forces (whether from the engine or from recovery of potential energy) is lost.

F Webe : Rule of Thumb: Gasoline Engine N/A: 1500-3500 rpm ~90% load Gasoline Engine Charged: 1500-3500 rpm ~75% load Diesel Engine Charged: 1500-2500 rpm ~80% load Comparing the specific Power shows, that there isn't that much of a difference between a N/A and a charged gasoline engine, especially if you consider enrichment effects. Rule of Thumb for real world driving: Constant speeds should be operated at as low as possible RPM, while the Engine still runs smooth. Usually everything above 1000 rpm is fine. Greater acceleration (e.g. >10 mph difference) should be operated at the given rpm range with the given load. A lot of Vehicles are geared for lower speeds, which means, that especially at highway speeds you often get relativly high rpm (2000-4000 rpm) and only about 50% load. In case of a gasoline engine this can be "fixed" with a transmission and differential of a diesel car, which can get you for example >80% load at ~1500-2500 rpm at constant speeds (e.g. Fiat Punto 1.4 16V N/A 95 hp with 6 speed MT from the 1.9 JTD with 120 hp). Pulse and glide would not be any more effective.

TwoScoops : I don't want to have to keep paying for gas how do I download more gears so it drives for free???

Danny Knapp : We're pretty obsessed with fuel mileage in the trucking industry. For large turbo-diesel engines and trucks, the biggest factor is speed due to aerodynamic drag. In a typical truck you lose approx 1/10 mpg for every mph over 55 you go. (It's not linear, but 1/10 is approx). Some engines prefer different rpm. A Cummins N14 likes 1400 rpm when loaded, while a Detroit 12.7 can be lugged down around 1200 or even 1100. You can get a visual clue as to what rpm might be best for your engine by looking at the torque curve data. Most truck diesel engines can be driven at very low rpms when the truck is unloaded. For loaded driving though, the key is slow acceleration, shifting at a bit above target rpm. Another trick is to ease off when going uphills and wait for downhill stretch to regain acceleration. I'm not knocking this video, it's great info. I just feel qualified to add my 2 cents because groups of truck-drivers have literally done hundreds of thousands of miles of testing, number crunching, etc... trying to get that extra 1/10 mpg. We've learned a couple things. Some of which is relevant to cars, some of which isn't.

B M : this is why i prefer manual transmission. the ability to choose. the ability to 'force' the car to ride at any gear

Backyard Chevy : You mean its not when the rpm needle is bouncing around the redline? lol....what car has 12000 rpm that u had to show all the up way to 12k did u test a motorcycle?

Sfekke : I was just looking for a video like this! Time to save on fuel when on the daily commute & floor it in the weekends to make up for all my savings haha Right on time :)

Got memes? : In my TDI golf i normally never go above 2000 rpm except if I have to accelerate faster like on 2 lane roads or highways