MPG at 80MPH?

This Graph is for a 2010 Gen 3 Prius Liftback, not a Prius v, so the numbers will be different. However I expect that the shape of the graph will be the same, it takes a LOT of energy to move air around the car at high speeds.


The Blue line is the mileage the computer reports, the green line is true MPG. (The Gen 3 Liftback computer has poor accuracy) The Liftback and V use very similar drivetrains but the v is heavier, less aerodynamic and has a shorter final drive ratio, all of which should lower these Liftback MPGs.

 

Bob Wilson put this graph together for the GenIII Prius. It relates well to other models. Simply drop about 7-8mpg for the Prius v and you will see the effects speed has on MPG. In summary, your mpg will be well below average at those speeds. I would think 30-35mpg wouldn't be too far off the mark depending on road/weather conditions. The good thing is, you won't get better mpg in any other car of that size at those speeds.

Many Prous owners actually change their driving habits after owning a Prius for awhile so who knows, you may actually slow down and get better mileage.

 

At least our story is consistent! I miss Bob Wilson.

 

Me too.

 

Congrats on your purchase. Got a great price on mine too, good stuff!

As far 80+mph commute, I drive around 95 miles round trip. My commute is rather hilly so the comparison is for what it's worth. When I drive between 80-90 mph, I get roughly 32.5-33.5 mpg. When I drive 70 mph, I get roughly 38-39 mpg. I'd much rather drive 80-90 mph but I've been doing my best to slow down (not easy for me to do).

The way I figured it, driving faster only saves me about 7 minutes each direction. Driving slower saves me about $.75 each direction. So at the end of my 4 day work week, it's either waste a total of 56 minutes or waste a total of $6.

If I'd just turn off all the mpg and consumption gauges, I'd feel less guilty for driving fast and getting relatively low mpg. After all, either way I slice it, my v mpg is WAY better than the 13 mpg I was getting in my truck.

Good luck!

 

I drove one high speed tank early on at northern winter temps (30-50F) and got about 40 mpg. My speeds were 70-75 mph. Anything higher I'd be off to jail if caught in these parts. We are a moderate area on hills. Temperature will also affect mpg as well up to 3-5mpg.

At 80 on flat terrain in a moderate climate I'd expect 35-38mpg. Please let us know what you see. I've read the Prius mpg improves after about 10k but I can't comment since I'm still at 1k. I did note a significant improvement when temps were over 70F.
W

 

Navy Seal – RE: “I just put a deposit on a 2012 Sky Blue Metalic Prius V, III - and I hope I made the right choice. My commute is high-speed, 80miles r/t averaging 80-85 mph open freeway, minor grade. My question is this; does the MPG a Prius gets go down after 65MPH? If so - by how much? Do you have any observations for me?â€

DaveShep and Wanderer’s posts have good information and advice for you.

Yes, of course, the MPG a Prius gets after 65 MPH goes down, as it would on any car. At travel speeds of 80-85 MPH and above, the Hybrid Synergy Drive (HSD) becomes, essentially, a “Boat Anchor.†At these high rates of speed, your fuel economy becomes the fuel economy inherent to the 1.8-Liter 2ZR-FXE (ZVW30) "Atkinson-Cycle" gasoline-powered engine, without any “HSD-MPG Magic.â€

Think, “What would I get driving a Corolla at travel speeds of 80-85 MPH and above?†lane:

 

May I add that this is absolutely true. The Prius v is not really a car that really encourage high speed driving. Besides, as you will find, the time saved by 80 MPH vs say 65 MPH is not all that significant.

 

I admit I've slowed down a lot since playing the mpg game against myself. I find I like not looking in my mirror for blue lights. W

 

They don't.

The hybrid system still functions as usual even at high speeds. The Prius would get even worse mpg if it did shut down. At high speeds the hybrid system is still contributing to increased efficiency but drag is so high at those speeds that mpg is simply going to suffer. I do not agree with the assessment that the hybrid system is a boat anchor at high speeds.

 

+1.

I went from driving 70-75 mph with my previous car (with my head on a swivel always looking for the state patrol) to being the slow guy in the far right lane doing 57-60 mph (speed limit 60). I'm averaging about 55 mpg (indicated - have seen as high as 58 mpg for the 34 mile trip) per trip to and from work with my V. My commute is 34 mi each way. It takes me only an additional 5 minutes per leg. I arrive much more relaxed...

 

They don't. It is still being used to help select an RPM for the engine and to capture energy going down hill or slowing.

MG2 is the bigger motor, it has a fixed ratio to the speed of the tires, 0 RPM = 0 MPH, 6500 RPM = 110 MPH (on a Gen1) But an electric motor produces maxmum torque at ~0 RPMs (Unlike a gas engine which usually has maximum torque near the middle of the powerband) so MG2 really helps at low speed and has a diminishing effect at higher speeds, but never no effect.

MG1 is not tied to the speed of the tires, so may well be at 0 RPMs at 100 MPH, it is harder to predict when it may be assisting at high speeds, I know there is a heretical mode, where MG2 is charging the battery and MG1 is providing propulsion, which happens at higher speeds (70s?)

How the PSD is like a Differential

What they MAY have meant is that when you are accelerating (which happens frequently in town) you are using battery reserves, and when you are cruising (at highway speeds or not) you are replenishing that battery. The Atkinson Cycle gets great efficiency when cruising but is poor at accelerating, so this is a fine trade off.

 

Good if you make less than $6 hour...don't get me wrong, I'm definitely part of the drive slower camp the older I get. Plus the added psychological and other benefits are definitely not accounted for in my $6/hour comment.

 

Just went on a cross country trip with some driving in TX where posted speed is 80mph. Got 38mpg with 3 people plus luggage. Prius did well even when I put 4500 miles on it in one week.

 

Texas is soon to have a stretch of highway running at 85mph. Is it out in the West Texas desert? No, between Austin and San Antonio running parallel to I-35. Obviously no real worries of Oil prices by the leaders (Republican dominated by Perry). Why do we need 85? Because it's a toll road intended to bypass Austin traffic. This very long bypass is built today and very few use today because it adds too many miles to the trip versus I-35 even with occasional traffic in the Austin area.

 

80mph = about 40mpg in CA. using ca gas.