Wait, What?? “Don’t” Hyper-mile in my hybrid? WHY NOT?

Good question, and I know it can sound crazy. There are a couple reasons why you shouldn’t – if your goal is to save on gas costs and get the most MPG’s. Hybrid vehicles have internal combustion engines (ICE). Sometimes these ICE engines are exactly the same as engines in the non-hybrid versions of your own hybrid vehicle. However, hybrid vehicles have ICE engines which are mated to an electric battery. This battery function is what is designed to to conserve on gas, reduce emissions, etc.

By not allowing (albeit inadvertently) the battery to do most of the work, the ICE compensates and defeats much of the battery’s intended purpose. I will explain more further down. But first, let’s quickly define what “Hyper-miling” is for those who may be unfamiliar.

Let’s define “Hyper-mile”

Well, first, I can tell you that Hypermiling is such a new term that my computer, as I type this, keeps telling me I have a misspelled word. It has those usual red dots under the term. You won’t see them, but I do.

Mirriam-Webster’s online dictionary has no definition (yet) for the word “Hypermile” nor “Hyper-mile”. But Mirriam-Webster’s does have a definition for “Hypermiling.” According to the well known and respected dictionary people, they define it as:

“: the use of fuel-saving techniques (such as lower speeds and frequent coasting) to maximize a vehicle’s fuel mileage”.

Mirriam-Webster’s Dictionary Online

Also, according to the Mirriam-Webster’s, the first known use of the word was in 2006. And I really believe they need to adjust the definition. Hopefully they read this article.

So you’re now probably wondering – “Why shouldn’t I use lower speeds and frequent coasting in my hybrid?”. So let’s explain.

Lower speeds

Lower speeds are a good thing, don’t get wrong. But it isn’t actually “speed” that results in the fuel savings of a given engine. Fuel savings of an engine depends on the gear that engine is in, and where that engine is with its RPM’s at any given moment. For instance: One could be traveling at a rate of 60 miles per hour (MPH), and another traveling at a rate of 30 MPH. One may think that the person traveling 30MPH is saving more fuel than the other person. Not necessarily.

What if the person traveling 60 MPH is in 10th gear, and as a result, the RPM is around 1200 RPM – and the other person is at 30mph in 3rd gear, but the RPM is at 1500 RPM? If you didn’t know what RPM meant, you might assume the 30 MPH driver was saving fuel. So let’s now discuss RPM, and what it is/means.

What is RPM? It’s an acronym used for “Revolutions Per Minute”

We all trust Cars.com, right? Ok, so let’s go with their definition, which is:

“RPM stands for revolutions per minute, and it’s used as a measure of how fast any machine is operating at a given time. In cars, rpm measures how many times the engine’s crankshaft makes one full rotation every minute, and along with it, how many times each piston goes up and down in its cylinder.”

Cars.com

Most of us are aware of that gauge (often with a needle) on the instrument cluster that works a lot more than the speedometer. It’s called the “tachometer”, and that’s what’s advising the driver of the current RPM for the vehicle’s engine.

Each piston has a spurt of fuel it combusts. If you have 4 cylinders, there are 4 separate chambers “cylinders” each combusting a spurt of fuel, in a sequence. Each full revolution of all of the cylinders combusting is 1, one, whole revolution. One. So, if you’re at idle, and you see the RPM (tachometer) reading 800, it means the engine, within a minutes time, at the current rate, will fire one entire sequence of all 4 cylinders firing – 800 times. 800 full revolutions, per minute. That’s a lot of tiny spurts of fuel. The same applies no matter how many cylinders an engine has.

The higher the RPM, the more fuel being used

Hopefully now you can see and understand that higher RPM’s is what will determine the amount of fuel one uses, and not just “speed”.

The goal is to stop spurting fuel

Anytime the RPM is showing anything more than zero, it’s using fuel. So, we want to have that engine off as much as possible. Traditionally, one who is hypermiling a non-hybrid, conventional vehicle, they would accelerate slowly. This allows the vehicle to work as little as possible to gain speed, resulting in lower RPM’s (less fuel being used). It makes complete sense – in a conventional non-hybrid vehicle.

In a hybrid, the goal is a little different. Although we want low RPM’s in a general sense, our goal goes deeper. We just don’t want to be using the engine at ALL, since we have the option. So, the faster we can get to a point where we can be in a position to let the engine shut off, the better. Right?

Comparing the acceleration of a non-hybrid and a hybrid

Let’s take one scenario. And lets apply 3 versions of driving to those scenarios. By the end, hopefully the point has been fully made.

The Scenario

There are three separate drivers. Driver A – who has a conventional non-hybrid and will be hypermiling. Driver B – who has a hybrid version of the same vehicle model, and will also follow the rules of the traditional hypermile. And Driver C – who will ignore the rules of hypermiling. All vehicles are automatic transmission. The terrain has light gradual inclines and declines, like normal.

All three will have the same goal, save the most money on fuel, with the most MPG they can get. They will be doing a straight route. The route is 6 miles long, with two stop signs equally in the middle (for 3 separate 2 mile stretches). The speed limit is 55 MPH, start to finish.

Are we ready? Let’s go!

Driver A (conventional non-hybrid) begins their journey

Driver A hypermiles for the first 2 mile stint before the first stop sign. Slow start, easing very gingerly up to 55 MPH, as softly as they can. Perfect hypermiling, and the vehicle reaches 55 MPH in about a half mile’s distance. They travel until approximately 1/4 mile prior to the stop sign where they ease down the speed gradually, until they come to a full stop. The engine was on the entire way. It had to be. They are in a non-hybrid. They repeat the process 2 more times to equal 6 miles and reaches the end.

It’s safe to say, they’ll be the one using the most fuel. They’re in a non-hybrid, and the engine worked the entire way, no matter how softly they pushed it.

Driver B (hybrid vehicle, will hypermile)

Driver B hypermiles the acceleration from the stop, just like Driver A. Slowly and gingerly, they also take a half mile to reach 55 MPH, leaving only one and a half left before the first stop sign. In that distance of the half mile, they were accelerating, slowly. But – the engine was on. It was working. Using RPM’s, and as we know, RPM’s are using fuel. Also, in that half mile distance, the route had a decline or two. They did this routine 3 times to reach the 6 mile distance.

Driver B was still accelerating during those first one or two declines in the road. They were attempting to traditionally hypermile and be as soft on the engine as possible. While they were soft on the engine, the battery had no opportunity to take over the duties and shut the engine off completely. As long as a hybrid is trying to accelerate to a highway speed, the engine will be on and working.

Driver B essentially only allowed 1.5 miles of battery only potential at highway speeds. In total, Driver B allowed for no more than 4.5 miles of the 6 mile journey for battery only mode opportunity.

Driver C (hybrid vehicle, will NOT hypermile)

Driver C takes off from a stop without attempting to hypermile. They aren’t drag racing anyone, but they’re getting up to desired speed (55 MPH) safely but with some authority. This driver wants to get to a point where the engine has the opportunity to actually shut off and use the battery – for as long as possible, and in battery only mode as fast as possible. They take a little less than 1/4 mile to get to speed. Now the engine has the opportunity to shut off just as the first decline of the road comes into play.

Driver C allowed for 1.75 miles per segment of battery only time. For the 6 mile journey of 3 segments, they allowed the opportunity for battery only mode 5.25 miles! This means the hybrid driver who was NOT hypermiling their accelerations allowed the vehicle to use .75 more miles for battery only opportunity than the one who was hypermiling.

The longer and faster a hybrid is traveling in battery only mode, the less gas it uses, while increasing the distance of battery only.

Conclusion – and “Hybridmiling“

I hope the illustration of the 3 different drivers in the scenario above has illustrated why traditionally hypermiling the acceleration of a hybrid vehicle is not the most advantageous method for conserving MPG’s. If you or someone you know may benefit from this article, please forward it to them via the links below or by any other method you choose.

Trukbed coins the word “Hybridmiling” to define this concept. Mirriam-Webster’s – Are you listening? 🙂

If you liked this Tip and Technique for getting the most MPG out of your hybrid vehicle, you may enjoy my other article. I explain the 25 TOP Tips and Techniques For Getting the MOST GMPG Out of Your Hybrid Vehicle Here: