How the Prius wastes fuel

[EVmetro]

I often come across eco drivers who do not respect the slower traffic kept right concept, or eco drivers that interrupt the flow of traffic because they are oblivious of anything that is going on around them. There are other vehicles that do this, but the Prius seems to be the main culprit. For years, I have noticed that when I come across an interruption in traffic flow, it is so often a Prius with nobody in front of him that is causing the problem. I respect eco drivers who can do their thing without interrupting the flow of traffic, but have resented the ones who don't for years. Anyway, I started keeping track of what happens when a Prius interrupts the flow of traffic a few months ago, and thought I might share it here.

One of the big things that helps out economy when eco driving, is to not interrupt kinetic energy, kinetic energy being "something in motion tends to stay in motion". A good eco driver knows to not speed up and slow down too much, and to use the friction brakes as little as possible, and this preserves kinetic energy. I have been researching kinetic energy usage for years in the electric vehicles that I build, so I have plenty of instrumentation on board my electric metros for measuring energy usage. I can plot and record graphs of my battery pack, amps, volts, rpm, speed etc, as I drive. When I encounter a Prius that is causing a resistance in traffic flow, I can see that the interruption of my kinetic energy wastes a few watt hours everytime it happens. It is not really all that much of a waste, and I can often make efficient driving choices to minimize the waste, but most cars do not.

Wasting a few watt hours everytime I come across a Prius is pretty trivial if you look at how it effects my fuel economy, especially considering that there are few EVs, if any, as efficient as mine, but if you imagine the number of gasoline cars that waste five times more energy slowing down to navigate past the Prius and the speeding back up after they are past, the fuel waste would be incredible. Wherever the Prius is, there is a resistance in traffic flow that wastes the fuel of all the cars that finally get by.

I see a lot of focus on weight and aerodynamics by those who are interested in fuel efficiency, but not a whole lot on managing kinetic energy. Many knowledgeable eco modders are aware that it is important for eco driving, but I am not sure if many realize just how much kinetic energy we waste while we drive. I have been studying it for years as I build efficient EVs, and I assure all that we waste way more fuel than most realize by not managing the kinetic energy.

[spacemanspif]

The speed limit is the maximum speed allowed on the stretch of road. Few roads have a minimum speed limit but they do exist. It's my opinion that if people paid more attention to the road in front of them and their mirrors that they'd be able to see the gap closing on the slower car, safely change lanes, and pass the slower car without ever slowing down. The waste of energy comes from poor drivers more so than slow drivers.

[Frank Lee]

Must be different out there. Most of the Prius' I see are driven like they're stolen.

[California98Civic]

Originally Posted by Frank Lee

Must be different out there. Most of the Prius' I see are driven like they're stolen.

Me too. Like they're stolen. See it all the time.

[Frank Lee]

Originally Posted by spacemanspif

The speed limit is the maximum speed allowed on the stretch of road. Few roads have a minimum speed limit but they do exist. It's my opinion that if people paid more attention to the road in front of them and their mirrors that they'd be able to see the gap closing on the slower car, safely change lanes, and pass the slower car without ever slowing down. The waste of energy comes from poor drivers more so than slow drivers.

It never ceases to amaze me how fast people crawl up my tailpipe, sometimes visibly slamming on the brakes before rapidly jerking the wheel to swerve around me. As if you couldn't tell you were closing in on me the last several miles until you were 20 feet off my bumper? Sorry to interrupt your texting. :/

[ME_Andy]

My father recently had the choice between driving a Ford Escape and a Prius on a 2000-mile road trip. He chose the Escape. ��

He's not a rich man... go figure.

[RedDevil]

Sorry to go off topic, but it suddenly occurred to me how many other interesting model names a PC keyboard can yield.

Ford Escape.
Starting the trend they took the key in the upper left corner.
Some racing organization claimed the next row of keys.
French estates are often called Break.
Suzuki has the Alt(o) and the Sh(/w)ift. Honda the Del (Sol).

But then. Who will claim Scroll Lock?
Where is the Nissan PageUp? Smart Alt Graphic? Chevy Control? Toyota End?

Back on topic.
I can see accurately how much fuel I use and how much speed affects that.
It seems that traffic in general moves way too fast.
That Prius, if it abides the speed limit, is not doing anything wrong.
If other drivers choose to ignore the speed limit and drive at a speed where they waste fuel by the bucketful, not anticipating cars up ahead that do move at a more reasonable speed, it is entirely their own fault.

There is a psychology factor too.
If the 'slow' driving car is anything other than a hybrid you would not register it as someone trying to save fuel. Just someone that drives the speed limit, for whatever reason, be it comfort, having the time, following the rules.
Maybe they like their car and are not in a hurry to abandon it at their destination.

But when it is a Prius you automatically assume it is to save fuel. It becomes an issue. And you remember getting held up by a Prius.
That's why it always is a Prius. You forget the rest.

Unless you drive at the speed limit yourself.
I cannot remember getting held up by a Prius in the last year.
I get passed on the motorway by at least 50 Priuses every day.

It all is just a matter of perception.

[MetroMPG]

I think people see what they want to see and conclude it's the dominant behavior: "disruptive Prius drivers" and "bad BMW drivers" and "Mustang drivers crashing into things when leaving cars & coffee events."

Confirmation bias: a tendency to search for or interpret information in a way that confirms one's preconceptions, leading to statistical errors.

[EVmetro]

Originally Posted by spacemanspif

The speed limit is the maximum speed allowed on the stretch of road. Few roads have a minimum speed limit but they do exist.

I agree.

Originally Posted by spacemanspif

It's my opinion that if people paid more attention to the road in front of them and their mirrors that they'd be able to see the gap closing on the slower car, safely change lanes, and pass the slower car without ever slowing down.

Again, I agree. If we had a world of good drivers who knew how to make the most of their fuel, everybody would share the rewards. I share your opinion, but unfortunately I can see that this will never happen in the real world.

Originally Posted by spacemanspif

The waste of energy comes from poor drivers more so than slow drivers.

This is where it gets complicated. You just summarized the types of drivers out there as either poor drivers or slow drivers, but this may not be reality. It is quite possible to have a poor driver who is also a slow driver, and it is very possible to have a fast driver who is a good driver. In the case of a Prius causing resistance in the traffic flow, if the driver of the Prius wishes to impose his idea of how people should drive, he will cause a change in the speed of the traffic that flows around him. This change of speed would not occur is all drivers were skilled eco drivers, but unfortunately the world is full of poor drivers.

[EVmetro]

Originally Posted by Frank Lee

Must be different out there. Most of the Prius' I see are driven like they're stolen.

I see a lot of Prius' being driven like they were stolen out here as well. Not every Prius is the problem, and much of the problem comes from other vehicles. My confirmation bias is what initially directed my attention to the Prius, but my research has shown that the Prius is indeed the dominant offender.