Suggestions/Ideas to improve Aero Drag on a RAV4 EV?

[RAV4 EV]

Hi Everyone,

I am interested in improving the aero drag on my Rav4 EV which is around 0.31 or 0.30. I would love to hear some ideas or suggestions on what could be done. I've read around Ecomodder and made a list myself but if there is anything else I'd love to hear it. Weight reduction wouldn't work so much for me as I tend to carry a lot of things with me when I drive.

Rear Wheel Skirts
Front Wheel Covers/Moon Discs/Wheel Skirts (If that is what they are called on the front)
Full Boat Tail
Side Mirror or Mirrors? Delete
Front Grill Block of some sort? (Partial or fully /w electric adjustable cover but unsure on how to read the temps from the rav4 ev)
Lowering the RAV4 EV (Suspension swap)
Dual Motors (Ok not an aeromod but if they can be more efficient than 1 why not?)
Taping smooth all panel crevices?
Door Handle Delete or cover?
narrow/skinny wheels and tires ?

Here is a good two shots of the rav4 ev








There is also this youtube video on how the drag was worked for the rav4 ev from the manufacturer

https://www.youtube.com/watch?v=ZN6qpUbba0Q

[Frank Lee]

You've hit all the big chunks with your list. I'd also suggest simply slowing down too as a means of not violently pushing so much air around.

It's .30 or .31 Cd BTW.

[Ecky]

A partial Kamm would be something you could attach quickly with a large return, while you build your boat tail.

[RAV4 EV]

Hi Frank thanks I changed that. I also tend to drive slow on FWY 50 to 55 mph and usually 5mph below speed limit on the city. Use regen breaks as much as possible hate using the physical ones.

Ecky doesnt the rav4 ev already have a partial kammback? I believe in the video they talk about it that or they call it a rear spoiler... is there a difference? Plus looked online for partial kammback pictures and it varies from just a sheet sliding straight out from the top to a more partial boxy design. How do you know which is best and how long it should be Plus angle?

[Ecky]

The rear spoiler is a partial Kamm, yeah. You could very easily extend it a few inches and see possibly measurable improvements in economy. Take a look at this 70+ mpg Civic:

http://ecomodder.com/forum/showthrea...avy-28815.html

[aerohead]

This is the K-form (Kamm/Koenig-Fachsenfeld) of the 1930s FKFS research,done next door to Daimler-Benz.

In side elevation,the car is an airfoil shape of particular fineness ratio.Any length of the body is a 'K-form',including the full tail.
Hucho recommends elongating the body along similar profiles,while pinching the width of the body in plan-view.
Your ultimate drag is a function of the length of the body.
As low as Cd 0.12 as shown in full length with all the other tricks (as a simple model).

[freebeard]

Chop the top.

It's hard to know what you best opportunities without what called a 'use case'. What kind of loads, what high of roadways, what kind of weather, etc. Some of the most effective things require commitment, like dragging a full boat tail around everywhere.

An alternative to lowering would be a full bellypan and wheelwell spats. but generally it should look like it's headed for the Bonneville Salt Flats.

What do you mean by Dual Motors?

[RAV4 EV]

Woah, chopping off part of the top is way out of my abilities. I sort of like the extra space inside... sort of why I replaced my Nissan leaf + a little extra range.

Dual motors refers to how the Tesla Model S has one electric motor for the front wheels and one electric motor for the rear wheels. There is a video online talking about how both motors are more efficient than one and overcome the extra wight of the motor. If you go to the Tesla builder site for the model S choosing dual motors increases the range by a little bit. So I was more joking in that having the same set up with the rav4 ev would be nice. It only is FWD.

The rav4 ev has a belly pan but I"m not sure how complete it is, but there is one. I believe the rav4 ev already has wheel well spats they are just kind of hard to see in the picture above. The video I linked should talk about them but here is a different shot. At least I think they are wheel well spats not sure how complete they are:



I've seen the K-form (Kamm/Koenig-Fachsenfeld) before and would love to follow the design!

Electric motor 115 kW (154 hp), 296 N·m (220 ft·lb)
Battery 41.8 kW·h lithium ion battery
Range 103 mi (166 km) (EPA rated)

https://www.fueleconomy.gov/feg/noframes/34425.shtml

76 combined city/highway MPGe
City MPG:78
Highway MPG:74

44 kWh/100 miles

The RAV4 EV has two charge modes: Standard and Extended. In standard mode, the high voltage battery charges only up to 35 kWh and Toyota expected the electric SUV to achieve an EPA driving range rating of 92 mi (148 km) for this charging mode. Extended mode allows the battery to charge to its full usable capacity of 41.8 kWh, providing an expected EPA driving range of 113 mi (182 km) according to Toyota estimates. The EPA rated just one range of 103 mi (166 km).

I have read about individuals who hyper mile with out any aero mods and have reached as high as 150 miles in ideal conditions. I am wondering what type of millage increase could be expected by adding a full boat tail + front and rear skirts? Probably also doing a partial grill block of some sort? For example what type of millage increase could be estimated by lowering the cd to sub 0.15 if it is starting at 0.31?

[Fingie]

Narrower tires could be a start. (dunno if feasible at the size of a Rav, tires are a lot expensive at SUV sizes)

How much heat does the engine or it's capacitors produce? Block the grille.

Minimize electrical usage by the comfort systems, like the cabin air con.
Have something cool the car @ home before driving off.

Full boat tail at that size could affect stability at strong crosswinds. Lower the car maybe instead?

Add green hubcaps for that eco-look and a EM logo sticker :P

[freebeard]

Dual motors refers to how the...

I hadn't notice it is an EV. I have a good candidate rear axle. It's from a Lexus SUV, and part of Toyota's Hybrid Synergy Drive. 98lb and 68hp. The only thing I don't like is it has an open differential. There are two eSUVs out now with dual motor/electric diff for limited slip. I think Toyota and Honda? I looked under a new Highlander and it's totally different to the part I have.

For example what type of millage increase could be estimated by lowering the cd to sub 0.15 if it is starting at 0.31?

There is an estimation that the change in Cd is twice the change in mileage; e.g. 0.1 less Cd means 5mpg. But that's for gas/diesel and mixes units and unitless ratios.

You vehicle has been aerodynamically optimized already, it would probably take four-wheel skirts and a boat tail to make much difference.