Coastal EV Mod - Has it improved your MPG?

I don't have the Coastal mod; I have a "home-grown" version. But no matter -- concept, benefits, and drawbacks are the same.

I find it most helpful during the early warmup stages of the car when the ICE will not shut down spontaneously during deceleration or braking. I am convinced it helps my fuel economy during these early stages.

Its benefit for me is probably better than for others because they also use an engine block heater to shorten their warmup time. I have an EBH but I can't plug it in at home or at work. I would use the EV switch substantially less if the car started out warmer.

It will work only at speeds of less than 34 MPH, so if you're coming down one of those long Sierra Nevada hills at anything higher than that, it won't help. Most of my driving is urban and suburban and I generally use routes where I can keep my speed below 34, at least during the warmup.

There also are other limitations the car imposes on EV use: battery charge too low, battery temperature too low or too high, and rapid acceleration among them.

I do NOT use it to force battery-powered propulsion except in very limited low-power and low-speed conditions when it might be less efficient to fire up the ICE -- e.g., to move the car around in the driveway or through a parking lot. To deliberately force EV propulsion normally will hurt fuel economy.

There are potential warranty issues. At least one PC member had a warranty claim for a bad hybrid battery initially rejected because of his EV button. Toyota later relented after he agreed to remove the button. See this for more.

EDIT: (I clicked "submit" prematurely.) Two things to consider with the Coastal mod: 1) It is not instantaneously activated; there is a short pause, 2 seconds IIRC, between pulling the cruise control stalk (through which it is activated) and activation. It doesn't seem like a lot of time, but when I want EV I want it now. 2) Coastal's customer service record is spotty at best. I suggest searching thoroughly to get a good sense of their customer service record before buying anything from them. Buyer beware!

 

I have the factory EV mod in our 2005. We live at the top of a hill, with about a 700 foot elevation drop over 2 miles to the freeway. If I have four bars on the battery I can get the car out of the garage and through the few little flat spots and humps in EV mode, then drive all the way down to the bottom of the hill without the engine starting at all. Since this would normally be warmup while traveling downhill it definitely improves mileage because I don't start the ICE at all for the first two miles. When it starts I'm usually getting on the freeway, where it will be used anyway.

The only minor gripes; the engine usually starts itself just before the bottom of the hill because the battery is "too full" (so if we're stopping at the bottom rather than getting on the freeway the ICE ends up running for about 30 seconds - not too good for it), and my wife doesn't like it on cold mornings because there is no heat until the engine gets warmed up.

As for other times, I use a manual version of what Toyota calls "SOC pre-staging for upcoming terrain." If I'm going up a hill that will allow EV (i.e. not too much power required, speed under 34 MPH), and I know I'll be going down the other side, I switch to EV mode so that I reach the top of the hill with about 3 bars. Then I continue down the hill keeping the speed at 41 MPH or lower (the speed at which the ICE starts to spin) to re-charge. I have found this very effective in terrain with which I am familiar. Around my house and work I know exactly how much charge I can use and get from each of the hills, and that allows me to maximize EV usage. Of course, I assume that this isn't going to harm the battery too much and that the management system will keep me out of real trouble, but that's probably not a great assumption. I do end up cycling the battery through a wider range of SOC than the management system will generally try to use, so it's definitely a case of caveat emptor.

Another use I make of the EV is to shut down the ICE manually before the management system does. This probably has a minor effect on overall mileage. But, if I see a red light ahead and I'm slowing to stop for it, I'll reach over and hit the EV button to shut down the ICE. I've found that I end up shutting it down from 15 to 30 seconds before the control system would. I've tried measuring the effect, but it is too small, given all of the other variables, to be noticeable in my mileage figures. The other uses give me about a 5-10% boost in overall mileage, depending on where I'm driving and how conscientious I am about using them.

In re-reading your post, a couple of other things to consider:

EV mode won't help on freeway hills, it's limited to 34 MPH.

The battery is too small to take advantage of really big hills, my home hill, with its 700 foot elevation drop will charge the battery from just over two bars all the way up to full (as shown on the MFD, so really 80% SOC). As a result, I frequently "waste" some of the downhills. Still, better than nothing.

It's not that expensive or that difficult to install, so it's worth trying. If you don't see any benefit then you can just not use it or take it out.

To get the most out of it, it helps to have some way of showing the recharge rate. Even if you can ride in another Prius equipped with a ScanGauge or other interface that allows you to see the battery current for just a little while, it will give you an idea of what various hills and slopes will do, how hard to ride the brakes for best effect, etc.

The people behind you will think you're an idiot for riding your brakes all the way down a hill, they'll just have to get used to it! I've had conversations with several neighbors who have noticed that I ride the brakes in the Prius when going down the hill, they're a more than a little surprised by the explanation. When I tell them that the engine doesn't even get started until I reach the bottom, and that the battery is fully charged when I get there, then they see the light.

 

I ordered and installed (with great emotional angst) the Coastal EV switch a couple weeks ago. It took a while to learn how best to use it, but I am noticing consistant higher readings for the first five minute bar. If I were to average that into overall MPG I would estimate 1-3 MPG depending on how many large parking lots you frequent !

The switch is activated through a sustained pulling of the cruise control stalk. Once you let the engine kick in through hard accelleration or exceeding 34MPH, the switch will not let you cut the engine off (when you come to a stoplight for instance) for a period of one minute, so you have to plan your use of it accordingly.

Running strictly on EV will deplete the battery rapidly above 5-10 mph, so it is has not a majic genie for me to significantly improve my MPG.

Having said that, I still LOVE IT !!

Jim

 

Totally agree!

I've learned to use mine in just the right instances, like leaving my driveway, neighborhood, and side street to the main road to work, or on the 1/4 mile steep incline to my office, and of course, all the big parking lots I regularly frequent!

I've learned to time using EV until just before the battery depletes below three bars, then I add coasting into the mix to charge back up - all while trying not to use the ICE. If I do deplete too far, I use neutral to stop the ICE from recharging like when I'm stopped at a red light. I'd rather it charge on acceleration(if I wasn't thrifty enough to stop EV before the batt got too low).

All in all. I'm loving having my 34mph stealth mode and believe with creative use, the EV WILL help mileage!
.

 

I think what you save in the first 5 minutes is most likely being added to the next 5 minutes.
I think the best time to use EV is.
1. Backing out of the driveway at 6.00AM quietly. (My driveway is along side (2 metre gap) my neighbour's bedroom.
2. Driving around the supermarket car-park. (showing off) car will most likely run in EV anyway.
3. In slow moving grid locked traffic. Again car would most likely run in EV anyway.
4. Leaving work car-park past workmates (showing off again)
5. sneaking up behind my son and his mates when he is walking home from school so I can scare him with the horn. (I'm a bad dad.)
6. Driving into my driveway at 3.00AM after a night shift.
I think Toyota did a great job of setting up the software in the car to run in the most economical mode all the time. I never use EV to try and get better economy. I also never drive more than 400 metres with the EV button on.

My car has EV as a genuine factory fitment.

 

Agree with the showing off patrs. LOL
Chuckle at the sneaking up behind son (bad dad) part. LOL -Something I'd do.

 

We live in a rolling-to-flat area and it has not helped our mileage at all. What I have noticed is that after using as much of the battery output as possible ("99.9" mpg for maybe as much as two miles) before the system demands charging, the mileage during charging decreases to about 25-30 mpg for the next 3-4 minutes - that doesn't help our average at all. It ends up coming back to our typical mileage of about 44 - 46 mpg.
My conclusion is that my implementation of the EV mode was strictly a waste of time and money. I don't regret doing it because I learned a bit more about the system.

 

Since all energy to move the car originates in the gasoline provided to it, how can the EV mode possibly result in improved MPG? There are many extra steps in the EV mode's mechanical -> electrical ->chemical ->electrical ->mechanical process, with all the attendant inefficiencies, for this to improve overall MPG compared to using the ICE to move the car directly.

 

In most cases it can't. However, the vehicle doesn't know how much longer or further you are going to drive it at any given moment in time, whereas the driver typically does. Additionally the vehicle doesn't knwo anything about the terrain, weather, or other driving conditions ahead, whereas the driver typically does.

Due to the lack of this information, the vehicle will occasionally run the Internal Combustion Engine (ICE) for reasons other than optimal propulsion. Because of the additional knowledge the driver can in certain circumstances tell the vehicle that it isn't necessary to run the ICE and therefore save some small amount of fuel.

A couple examples:

You are moving the vehicle out of the driveway and back so you can get some other vehicle out of the garage. The Prius doesn't know that you aren't about to set out on a 600 mile journey, so it runs the ICE in a rather inefficient manner to get the engine coolant and the catalytic converter up to normal operating temperatures. Using the EV mode allows you to avoid wasting fuel to heat up devices you aren't going to use.

You are early in your trip and the vehicle has not yet reached the appropriate operating temperature and idle check to enter S4 operation. You are about to head down a long hill to a stop light at the bottom of the hill, the ICE is running and you haven't exceeded 34 MPH since your last stop. Since the Prius is still in the process of warming up, it continues to run the ICE burning fuel while gravity pulls you to your stop. The car doesn't know if you are about to move your foot to the gas pedal or if you are planning on stopping ahead, nor does it even know that you are on a hill. Since the vehicle doesn't know if you might want to accelerate at any moment, and since it needs to heat up the ICE anyhow, it keeps the ICE running unnecessarily just in case. By using the EV mode at the top of this hill, you can travel all the way to the stop at the bottom without using any fuel and the battery will be plenty charged from the process of slowing down the hill. Then when you accelerate from the stop at the bottom the ICE can turn back on to continue the warm up of the ICE when it would have been used anyhow.

 

That's a good use of the EV Mod. Used inappropriately, the EV mod can easily hurt your mileage. I rarely use mine, except when I need to move the car a short distance for a brief time. In stop and go driving, it probably doesn't pay to use it.

 

Exactly. There are a few specific situations where, if the driver truely understands the operation of the vehicle and has enough information available to make the decision, the EV mode can reduce fuel usage.

On the other hand, simply driving around with the EV mode turned on whenever possible will almost always result in increased fuel usage in the long run (and lower MPG for any given tank).

On the other hand, there are times when I'm pretty sure I'm hurting my MPG but choose to use the EV mode anyhow. I like the way the car attracts attention when the ICE is off while driving into or out of a gas station or while driving past someone in a parking lot. My nieces and nephews get a kick out of seeing the car pull away without hearing the ICE kick on (as do a few other family members). These situations are infrequent enough and low enough power that the effect on my fuel usage seems negligible.