Do wind deflectors work

[Jolly English Gentleman]

After coming up to 8 years of ownership, I am looking at replacing my soon to be 11 years old 2nd Gen T Spirit.

Naturally it will be replaced with another Prius and am looking at a 4th gen . One of the models on my radar is a Business Edition Plus demonstrator that has a few extras including wind deflectors fitted against a slightly older Excel that has no extra goodies.

Has anyone any experience of wind deflectors? Do they work? Do they affect the fuel consumption? 

[RUToyota]

I have them on my Estima...and love them.

Don't see how they could affect your mpg negatively tbh.

I like to be able to open the window partially and not get any irritating wind bashing..

[PeteB]

I haven't checked recently, but at launch a Gen 4 Prius (on 15" wheels) was in the top 5 best production cars for low aerodynamic drag, matching an all-electric Tesla Model S which has a distinct advantage of not needing a radiator grille or exhaust system under the car.

The development needed to get the Coefficient of Drag (CD) from 0.25 (Gen 3 Prius on 15", which at one time was in the top 10 best) to 0.24 was quite significant.  Even the plastic wheel trims, position of the rear wiper when parked and lots of other tiny details all add up to this remarkable figure.

Below 0.30, these small numbers mean a huge difference, and as the number get smaller, I think I'm right in saying the significance increases.  For example, I believe the improvement from 0.26 (gen 2 Prius) to 0.25 (Gen 3), was not as big a change as the drop from 0.25 to 0.24 of the Gen 4.  (any aerodynamicists in our midst care to comment?)

Bearing that in mind, I find it hard to believe there isn't some cost of having the deflectors in the first place, opening a window would probably increase that difference a little more.  But, I believe these losses are likely to be so small, I doubt they would be measurable in displayed or tank to tank mpg calculations.

[Duffryn]

No experience of Gen 4 at all, but I had wind deflectors fitted on my previous 2010 Gen 3 Prius (included as part of the purchasing negotiations!). I don't have them on my current Gen 3 Prius, and, comparing the two cars mpg's on Fuelly website the figures are turning out to be almost identical - ie the deflectors didn't appear to adversely affect the fuel consumption much, if at all.

When I bought my current Prius I tried to include having deflectors fitted as part of the 'negotiations', but unfortunately the (different) dealer would have none of it. I still miss them and would have them again, but IMO Toyota retail prices are bit too steep.

[crofter]

Hi John have you looked at deflectors at Climair.com I have had them on quite a few of my motors  in the past and have them on now they are of German make and are not stuck on but fit in the window channels and well made

Del

[unclepoo]

I had Wind deflectors on a pajero I had a few years ago. Was nice to have a window open a small amount without noise etc. The only problem I found was, as the pajero is a japan domestic market vehicle, the deflectors were larger than the UK deflectors for the shogun. So they were just in my eye line when looking right or left.  So check this when you`re sat in the prius with the seat exactly as you like it.

As for wind deflectors affecting the fuel consumption of a pajero....that`s a laugh.  

[Jolly English Gentleman]

1 hour ago, crofter said:

Hi John have you looked at deflectors at Climair.com I have had them on quite a few of my motors  in the past and have them on now they are of German make and are not stuck on but fit in the window channels and well made

Del

The question only arises because one of the vehicles I am considering already has them fitted. I don't think I would go out my way to have them if they were not already on the vehicle, but thanks anyway. 

[Jolly English Gentleman]

1 hour ago, unclepoo said:

I had Wind deflectors on a pajero I had a few years ago. Was nice to have a window open a small amount without noise etc. The only problem I found was, as the pajero is a japan domestic market vehicle, the deflectors were larger than the UK deflectors for the shogun. So they were just in my eye line when looking right or left.  So check this when you`re sat in the prius with the seat exactly as you like it.

As for wind deflectors affecting the fuel consumption of a pajero....that`s a laugh.  

Thanks for that. I am hoping that I can persuade the dealer to secure the vehicle (it is at another dealer some distance away).  I am looking at two potentials. The one with the wind deflectors is newer and has less mileage, but is a slightly lower manufacturer specification hence the two vehicles being within £7 of each other. The ideal situation would be for the two dealers to do a straight swap, but I expect that would be too easy. 

[Jolly English Gentleman]

10 hours ago, Duffryn said:

No experience of Gen 4 at all, but I had wind deflectors fitted on my previous 2010 Gen 3 Prius (included as part of the purchasing negotiations!). I don't have them on my current Gen 3 Prius, and, comparing the two cars mpg's on Fuelly website the figures are turning out to be almost identical - ie the deflectors didn't appear to adversely affect the fuel consumption much, if at all.

When I bought my current Prius I tried to include having deflectors fitted as part of the 'negotiations', but unfortunately the (different) dealer would have none of it. I still miss them and would have them again, but IMO Toyota retail prices are bit too steep.

I am looking at an Excel with no extras against a newer Business Edition Plus that has several extras with less mileage at another dealer some miles away. The two are priced within £7 of each other, and I am hoping that the dealers would be willing to swap them so that I can get the one with the extras, but that would probably be too easy.

I do find that dealer prices can vary significantly. My nearest dealer seems to be one of the most expensive in the country, but fortunately there is a more competitive dealer who I am speaking to not too far away.