2019 RAV4 Hybrid Limited
 

Went for my first hybrid and I’m loving it. Hypermiling the best I can and running on 91 octane fuel with tires at 48psi, I am getting 49.5 mpg average per tank as indicated on dash. I was wondering if there would be any suggestions on what to try to improve aerodynamics? I know it’s higher in the air, which makes it easier to get in my driveway, would lowering it or putting an air dam help? I’m contemplating a partial grill block to help smooth out the front, but don’t want to hurt the a/c function as I’m in AZ and need it bad. I have taken off the roof rack that came factory. I’d really appreciate any and all ideas!

I probably wouldn't mess with a grill block in AZ, and especially in a new car. You sure it doesn't have an active shutter? Many newer cars are starting to come with them.

50 MPG is crazy good. My Prius gets that.

RAV4
 

clean up the belly,add rear wheel skirts,then 3-feet of boat tail.

What aerohead said, plus wheel spats.

I'm curious about the the rear drive. Does it have a driveshaft or an electric rear axle?

I expected it to have the active shutters, but it oddly doesn’t. The grill is blocked on the right and left sides a bit as in it’s not hollowed out and just has the grill look to it. Was thinking of at the least doing a smooth block there just for aerodynamic effect if it would have one at all. Also with the fog light cavities, I was thinking of getting some thin plexiglass and forming it to fit and siliconing it in to smooth it out too.

Any suggestions on how to add some sort of shield over the wiper blades? Thought that might help smooth it out too.

From my understanding, it is pretty smooth on the bottom with the factory belly pan. Any advise how I could help reduce drag for it being so high off the ground? Do some sort of block in front of the tires like the eco Corolla’s have? What about a short-ish airdam? Would that have the same effect as lowering it sort of?

Would taller tires help? Or smaller, low profile ones? I know I want to get the low rolling resistance ones when the factory set give out.

Thank you for the recommendations and advise. Really trying to understand and use the information.

wiper blades
 

I tested for this and found no improvement.Even adding a more streamlined windshield along with it only lowered drag 0.005.

How about partial wheel arch covers? Smoother wheel covers (maybe black inserts for the gaps in the rims).

The wipers appear to already be out of the path of the air to my eye.

With Toyota's HSD, there's no benefit in terms of gearing with larger tires, since the engine has no fixed ratios with the wheels. In theory a larger diameter tire will have lower rolling resisting but is heavier and with a higher moment of inertia. A narrower tire has better aerodynamics but requires more pressure to get the same load rating. I wouldn't go significantly different from factory size.

I would very much like to lower the wheel arch gap if I can. Been thinking of getting some ABS plastic that matches the fender flares and trying to fabricate some that would look seamless. Not too sure how to work with ABS plastic though. Thinking I can score it, bend it to match the curve, drill holes to match the existing wheel well fasteners, and go from there. Wanting to make it not stand out too much if at all.

As far as the tires go, I found out that they just have pretty standard all season tires on it. In AZ where it doesn't snow and barely rains, I'm thinking a low rolling resistance highway type tread would be the way to go. I was thinking of going with a taller, narrower tire if I could fit it on the same rim.

I saw the idea on here of sealing the panel gaps. Does that really help much? I decided to take some rubber door edge guard and put that around the gap of the hood to the front fenders/grill. Don't know if I'll see much difference though. Was thinking I could get the same stuff and wedge it in all the gaps. Use a clear or something. I'm just not sure if it would be worth doing though. Being a new car, they're pretty tight already.

With the underbody already being smoothed out with the factory belly pans, would an air dam be any benefit?

I'm also wondering how I could safely add additional battery storage to the hybrid system and add a grid charger as well. Ideally, be able to have the grid charger only charge the "extra" set of batteries so I can mitigate the risk of damaging the battery pack that came in the car. I just have no knowledge of electrical systems unfortunately.

As early as the 2nd gen Prius, people have been adding secondary packs and making them into PHEVs of sorts. I'm unsure how much the 2019 differs from other model years but that kind of conversion isn't something easily done as a one-off, even with a degree in electrical engineering. Wait a few years and kits might become available.

I did this, but in sheet metal:

If you cut a semicircular strip with the same radius as the wheelwell arch it will lay flat. If you use a straight strip and bend it it will stand out at 90°.

But if the strip is circular but with a larger radius it will form a conic sector at some arbitrary angle.

Sounds like adding the extra batteries won't be a great option. Or even grid charging the internal ones.

I'm thinking more and more about biting the bullet and going for the wheel arch covers. I know the back ones can come down as far as the bumper/door, but what about the front wheels? I really don't want to make it look weird or impact turning. Thinking I should just come straight down with the addtional material and have it come close to the tires, but still above it. Any suggestions on how far above the tire to go? Maybe 4 inches or so?

I would get under the front end and measure how much travel room there is between the upper bump stop and whatever suspension component moves up into it. Most late model vehicles have very little upper suspension travel. My guess is you will only have 2-3 inches of travel at best. Take whatever measurement you get, add an inch to account for some compression of the rubber bump stop, and that's how far above the tire I would start out with.

I would not expect there to be any easy mods for you given the CAFE standards automakers must meet.

You may be able to get some gains from adding positive rake to your vehicle, though it may already be like that.

That sounds like a great way to measure how far down to make the fender flare extension. Thank you!!

Could you explain more what you mean by "Positive Rake"?

This is when the front of the car sits lower than the rear. More air goes over the car than underneath this way. You can see if you have positive rake by measuring the distance in between the middle of the hubcap to the gender, then comparing front and rear measurements. If they are the same, you do not have any rake.

There's a joke in there somewhere.

I'd go with the distance to the ground ant the front and rear of the rocker panel.

The traditional gauge was a pack of cigarettes. Upright = low, on it's side = lower, laid flat = one step short of laying frame.

Look closer--it does:

https://ecomodder.com/forum/member-v...l-shutters.jpg

Toyota lists them on all trims of the 2019 Hybrid (it would only let me display 3, but the XLE has them as well).

After I had seen the post about how it should have the active shutters, I pulled up the same resource actually. I looked closer at my vehicle and saw it does hav them, but not to where they would actually help anything. They're on the lower grill but it's so small, I doubt they'd do anything. And they're behind the grill, so it's not like they would smooth out the air much I don't think.

Toyota wouldn't include them if they didn't help anything. It's another expense, and another failure point covered by warranty service.

It's true that placing grill blocks in front of the grill is aerodynamically better, it still is beneficial to place them behind. There's still the benefit of faster warm-up too. The shutters need to be behind the grill so they are protected from damage.

GK13 - did you do any mods yet?


I'm curious why you're interested in taller tires? If it's for gearing, I doubt you'd gain any advantage there as the eCVT generally aims for lowest engine RPM under low load conditions regardless of cruising speed (notwithstanding generator requirements to charge the hybrid pack). I suppose at some point you would max out the gearing range at high speed.


Also, raising the ride height will likely increase drag some.

I haven't really been able to find any good mods to do. I did get a scan gauge and that has been nice. Putting extra air in the tires helped some. Main thing thing that seems to help it is hyper-mile driving by tricking the car to go into EV mode from gas.

I do want to try doing rear wheel skirts but haven't really had time or knowhow to attempt it.

With the tires, I think you're right. I shouldn't go as tall as possible, but will probably find what tires I can get with the best low rolling resistance, most quite and comfortable ride, and best wear life. But, I can not seem to justify buying new tires when these hardly have 3k miles on them.

I am considering some kind of grill block as well. I'm not too sure what else I can really do to it to make it get better mileage besides adding more batteries to it. I'd love to add more batteries, but don't really know how I would do it. It also seems to be cost prohibitive. Doesn't seem like anyone is doing the retrofitting of additional batteries any longer.

Before we can recommend modifications, it would be good to know why you want to improve your MPG. There are generally two camps here on ecomodder:
1. Those that want to modify their cars to get better fuel economy so they can save money.
2. Those that modify their cars just to try to get the highest MPG they can without consideration of whether they will ever recover the money spent on the modification in fuel savings.

You are driving a vehicle where even a relatively large MPG improvement like going from 50 mpg to 55 mpg returns a very small savings. Driving 10,000 miles per year and paying $3 per gallon you would save about $55 per year. Going from 25 to 30 mpg on the other hand saves $200 per year. Going from 15 to 20 mpg saves $500 per year.

Tires are a good example. You can likely improve your fuel economy by 5-10% by switching to narrower tires with a lower rolling resistance. However, those tires will cost $600 - $700 and last about 60,000 miles. Does it make sense to you to spend $600 to save $330 in fuel? That depends which camp you are in.

Your active shutters still save fuel because they trap a pocket of still air in front of the shutter. Yes, it would be a bit better to have the shutter on the outside of the grill but Toyota decided that small gain wasn’t worth the downsides.

I have a mis-matched pair of Dish antennae (One is round, one is oval). They're about the size of a wheel and the backside is convex. Hold an appropriate one up inside the wheelwell and draw a line with a Sharpie. Cut it outside the line and add Dzus fasteners. Paint to match.

With a mismatched pair I'd thought to use one as a fiberglass mold.

I would say I am in between both camps as I look at the financial aspect of it being able to recoup the cost, but then it is a game to me seeing how high I can get the MPG.

I won't be doing the tires any time soon as I don't want to just waste the tires it came with. Thats where I am in the 1st camp. But, if I can do some other mods to the car that don't break the bank, I will certainly do them.

I think the main thing I'm interested in doing would be increasing the battery capacity and turning it into a PHEV instead of just a HEV. I of course would like to see what kind of "low hanging fruit" I can find to help with the aerodynamics of it. Like I was seeing that it's not a full belly pan when you get to the exhaust. I'd like to see it up on a lift to see where I could add more smoothing on the bottom.

What I want to do with the wheel skirts is make something that almost looks like it could be stock. Something that goes with the body lines and doesn't stick out like a sore thumb. Trying to find that middle ground with my car. Functional as intended, but better MPG than anyone else's.

[Challenge Accepted]

https://ecomodder.com/forum/member-f...e8467-rav4.jpg

Drop it a couple of inches, too. "Perfect."


I'd love to see someone get out the angle grinder and chop a coil or two off a brand new RAV. :D

You took what I had in my head and put it on paper! Now, how in the heck to build it?!

I have thought about lowering it an inch or two, but I kinda like the height as my driveway is a little steep and most cars scrape going up. And it’s nice not having to crawl out of a lower vehicle being over 6”

A Photochop. Never touched paper. :)

Four wheel spats can substitute for the lowering; but, hey — stance.

If this vehicle has the twin-motor rear axle, I'd be interested in a photo or diagram. It should be perfect for EVing an old Beetle.

How do you think I can go about making the rear wheel skirts look like that? I think it could be done, but would need to be done right in order to last and be useable for tire changes and such.

https://ecomodder.com/forum/member-f...9-100-0629.jpg

What I have done is use redwood strips to mock up contours.

I'd start by placing something with thickness to show tire clearance over the wheel and tire and then tape strips to the bottom edge and that raised rocker panel character line to see how much bulge you'll need.

That recessed panel could be pulled out and the character line may clear so you can just undulate the lower part.

Fiberglass and a lot of time spent making it look presentable.

Is the Rav4 Hybrid the new Prius?

The sales numbers would seem to say so. I wonder if the owners are as enthusiastic about MPG as early Prius owners were.

I took a look at one of these in a grocery store parking lot. Sure enough, the back of the tire hangs out of the body lines.

It would be a Turnpike-cruiser style bubble skirt. The recess panel becomes a problem.

When I look at mine, the wheel seems to sit inside the wheel well enough that a panel could be put in place. I'll have to look into it with more detail and time to come up with a prototype.

What about a front air dam? I know that its all smoothed pretty much underneath but is raised up fairly high off the ground. I don't really want the expense of having to lower the vehicle and sacrifice ride comfort.

Only way to know for sure is to test it.

I've found air dams have helped on multiple vehicles, even ones that extend well below the lowest underbody component: Firefly/Metro, Mirage, Micra, Miata. (Hmmm... lot's of "M" cars!)

I tested the air dams on these either with multiple coast-down runs, or with multiple constant-speed MPG runs. Always tested on the same route, same day (same ambient conditions).

But on one vehicle I tested, an air dam appeared to make things worse: 2004 Toyota Prius.


Moral of the story: make one and test it out!

I’m looking at what it would take to do an integrates boat tail from the rear wheel skirts. Maybe have them come off of some OEM mudguards. What do you think?

A proper boat tail covers the full width and height of the tail. A hitch receiver or underbody difusser might be a better foundation.

A boat tail can just underlap the skirt, so it is separately removable.

Ok. Thank you. Now, do the window visors add drag? or do they not really effect anything? Haven't seen a conclusive answer yet.

After looking at the back of the RAV4, it seems it ever so slightly has a boat tail to it. I’m curious now, if I was to somehow extend it, if that would help anything? And how to do it without blocking visibility? Maybe out of thicker plea glass or the like?