2020 Prius Prime- Looking for tasteful Highway aeromod

[Fat Charlie]

Aeromods in heavy traffic?

Seriously, if you have to stay in the high 70s to keep from becoming a statistic, the surrounding traffic is your aeromod. You've got the corridor effect going on: cars in front, behind and all around. Not that it's a cure-all. I've found (in my car, on my roads, YMMV) that drafting a good 18 wheeler is good for 10 mph. That's best case- drafting behind a big rig at steady speed, I get the same mileage as I would hypermiling in open air at 10 mph less. So behind a truck at 70, I'm getting what I'd see on my own at 60.

Except your corridor isn't made by professional drivers at steady speeds, it's made by psychopaths that make it unsafe to drive more slowly. So you're not going to get optimal results from that corridor. But in traffic that heavy, I think aeromods are a waste of time.

[freebeard]

I've found (in my car, on my roads, YMMV) that drafting a good 18 wheeler is good for 10 mph. That's best case- drafting behind a big rig at steady speed....

Back when I could go out on the Interstate (), I found the best result with a full-widith half-height load on a flatbed. Less buffeting than with a full-height box van.

[gregersonke]

Update, I did digging, worked out some visuals. I installed a few vortex generators around the center behind the antenna in the back plastic piece with a separation of about 11 inches at the farthest points. Gave them about 20 degrees angle. Doesn't really change the fuel mileage much if at all, but certainly seems to increase the wind envelope stability when passing trucks, etc. I didn't have a ton of cross wind today. But I'm hoping to see how well it does in the nasty crosswinds we have been getting as of late.

[GreenTDI]

Originally Posted by Fat Charlie

So behind a truck at 70, I'm getting what I'd see on my own at 60.
.

18 wheelers going 70 mph? That even sounds dangerous. On the other hand, driving behind such a monster at that speed is some serious hypermiling! In Europe they're all limited at 55 mph.

[ksa8907]

As mentioned in other posts, not much to be gained from increasing mileage from that point. If gas is $4/gal and you make the MASSIVE change from 45mpg to 60mpg, over a 180 mile trip you'll save $4.

The question becomes: at what effort/cost?

[RedDevil]

Originally Posted by GreenTDI

18 wheelers going 70 mph? That even sounds dangerous. On the other hand, driving behind such a monster at that speed is some serious hypermiling! In Europe they're all limited at 55 mph.

70 mph? Going down a mountain on a straight highway you better keep an eye on your mirrors no matter what speed you're going. The semis use gravity to get to extreme speeds. Something you have to be aware of if you rent a car in the States as an European. Some I've seen fly by must have hit 100 mph or more.
Also, if you are on an incline near the crest of a mountain and there's a semi climbing slowly up ahead, better not pass but stay behind it.

[redpoint5]

Once when I was 15, I was driving the family van north on i-5 coming down the Grapevine at 80 MPH, and was passed on the right like I was standing still by an 18 wheeler.

Generally the speed limit for tractor/trailers is 55 MPH and they do 60. On roads where the limit for everyone is 75 or 80, I see the truckers going 70 or more.

[gregersonke]

Originally Posted by redpoint5

Once when I was 15, I was driving the family van north on i-5 coming down the Grapevine at 80 MPH, and was passed on the right like I was standing still by an 18 wheeler.

Generally the speed limit for tractor/trailers is 55 MPH and they do 60. On roads where the limit for everyone is 75 or 80, I see the truckers going 70 or more.

The grapevine is a dangerous place for truckers. The one that passed you may have very well lost his brakes or other serious issue.

As for where trucks tend to speed, it's kind of the same as we cars. Where it's plain and simple safer for them to do so they will. Where it's not, they won't. Truck drivers in general are significantly safer drivers than car drivers. It's not 100 percent, but statistically, they are a lot safer per mile than car drivers. The big thing with car drivers, they need to be aware of what trucks will need to do in a turn etc. Aka, if you are on a wide freeway exit, don't pass them on the right. Wait...

[gregersonke]

Okay, my vortex generators were apparently more effective than I thought they would be. Consistently, I just recorded two back to back record fuel mileage days doing the same 80mph speeds on the same route. Even going directly into the wind I'm getting well into the 40s where before I'd be in the 30's. Going with the wind is better too, the window in the back seems to stay a bit cleaner too. I think I'm going to make something like the toyota prius TRD roof garnish, but a bit smaller as it's become apparent that I can use the small window bubble down effectively to achieve the result I want.