Prius on highway - a bit of disappointment

I've noticed variations in the road surface create a wide range of noise levels. I test-drove a Corolla before I bought my 2011 Gen III and the Prius was much quieter than either the Corolla or any of my old vehicles.

Asphalt vs. concrete -- it can make a big difference.

Changing the tires may help, or you may want to double-check the tire pressure -- some have reported that running at 42/41 may reduce friction and thus reduce noise.

 

Nobody gets 50+ mpg at 75mph, the wind resistance at that speed eats into gas mileage, want better gas mileage, slow down.

 

I had the same issue I just spent the day sound deadening the doors and rear floor area.
with a I phone decibel meter before I did any thing I drove a 10 mile loop around my house the meter would hover around 76 to 79 with a peak of 88 a rough patch of asphalt.
after the work the meter was reading 64 to 72 with a peak of 80. I plan on taking a look at the front under the carpet and kick panels tomorrow I believe thats where a lot of the road noise is from mainly around the wheel arches.

 

Once you get over 65 mph, the aerodynamics of the Prius itself loses efficiency due to the excessive wind resistance, and fuel efficiency starts dropping dramatically. Of course, this happens to all vehicles, so imagine how bad it drops off for other vehicles?

As far as sound dampening, the Prius does seem to be a bit light weight in order to gain maximum fuel efficiency, so I figured the excessive noise was down to that.

 

51 City, 48 highway, 50 combined...

Sounds to me like your Prius is doing just fine.

 

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If you are getting 48 MPG at 75 MPH you need to share the secret. I usually get less than 45 at that speed. At 65 or 70 I may get 46 to 48 on a good day.

I think the EPA runs their highway test at 66 MPH equivalent. But they don't actually go out and drive the car at 66 MPH and check the mileage, they run it on a dyno following a computer program and factor in the CD to account for wind resistance. Their numbers are good only for comparison.

I have had 3 sets of tires on my 2010 and I noticed no difference in noise, it was noisy with all three. I think the only way to reduce noise is, as mentioned above, to use sound isolation. The Prius is just a hollow "tin can" with little or no sound deadening material.

 

At 75 mph, a lot of the noise is caused by the low rolling resistance tires. If you get a set of tires designed for higher speed, the noise level should be reduced somewhat, but so will your MPG.

If you want to keep the Prius, then cruise at 65 mph.
If you want to cruise at higher speed, buy a different automobile.

Whether you keep the Prius of trade it in for another vehicle, at 75 mph, wind resistance becomes a significant factor and you will get lower MPG.

Suck it up, and quit whining.

 

2011 prius is EPA rated: 48 highway!

 

I used rammat it is like dynamat but much cheaper he also sells the self stick foam to put over it. it makes the car feel more solid and now when you shut the doors they sound like a lexus not a can with a rock inside.

 

I am a lead foot and drive both highway and city. I only get 42 to 49 mpg on a tank. There is no other car in the world that I can afford that will get me that high milage with my driving habits. And one cant expect great milage going fast, stopping and starting, or living among hills. Which makes me believe that the Prius is a great all around car and works out for all types of drivers. But I still have a pickup to do the hauling and run errands.

 

From http://priuschat.com/forums/other-c...uth-about-epa-city-highway-mpg-estimates.html that I posted earlier, the highest average speed on any of the EPA test cycles is only 48.4 mph.

 

Thats great information! Very good article. Thank you cwerdna!

Gives great insight into the science and how science and reality rarely ever meet.

I understand standardized testing, but they should at least take one for a drive.

 

After having this car for just about a month -- and 1300 miles ........

If I had a high speed commute ...I don't think this would be the car I would want ... especially over rough or concrete roads ....maybe a leased VW TDI that went back when the warranty was up.

But for mixed driving -- this car really shines ..... And on newish asphalt highways .. the car is pretty good.

My SUV get around 14MPG and my Sedan maybe 15MPG -- so 47MPG is quite amazing ...and it takes regular.

 

I had the same complaint with the Yokohama Avid S33D tires that came on my 2010. I feel like the Michelin Energy Saver A/S tires are a bit quieter, especially at higher speeds. As someone else noted, road surface makes a huge difference. Typically, concrete results in a louder ride, and fresh, new asphalt is going to be your quietest.

I, too, would like to have a bit more insulation or sound deadening material in the car, but I don't find it to be noticably worse than any other car I owned, except maybe the Nissan Maxima.

 

I always use PWR mode on the highway but I'm happy with 40+ this car rolls nice at 75-80! Noise could be tires? Good luck.