Terrible 3rd Gen MPG ...according to Consumer Reports

Yes we know Consumer Reports MPG test is crazy/nuts on the Gen3 City Driving test at approx. 32 MPG.

 

Right it was equal opportunity hitting other makers/models too.

Where I come out on it, forget the CR city rating...possibly the CR highway rating (55 MPG for Gen3) is valid for comparing against different models. That gives us 55 vs 59 (Gen 3 vs. 4) ...that's better!

 

I sincerely believe I could duplicate CR's numbers: if you slam on the brakes at the last second, they are always friction brakes and never regenerate any electrical power. (Full throttle would be the equivalent, but will have less impact than full braking)
So, avoid steady speeds, never coast, never gently brake, and always have your foot to the floor. you too can get that 32 MPG!

Rural mail delivery has a similar driving cycle and they get about 37 MPG without working as hard as CR does.

 

Ah, when I had my 11 Prius 2 for 2 and a half years I averaged 44 mpg, matched Consumer reports, the two caveats are 1, I live in L.A. and 2 I just drove the damn thing and kept up with L.A. traffic.

 

I'm not a fan of CR, but at least their tests are as close to the same as they can get, so the data is at least useful for comparison purposes.

 

But their City MPG test is so wacky, any comparison probably better just use their Highway test.

 

I get that, but it's not designed to estimate mileage, etc., just to show how a vehicle performs under the same conditions as another. And if you're comparing 2016 models to previous models, the CR city average is just as applicable as the highway average when determining if the 2016 gets better mileage than earlier models. You need to have some baseline, no matter how wacky.

 

Wonder if they tested the Gen 3 in the winter... it can get cold in CT/upstate NY. Winter sure kills mileage

 

Also snow on 'roads kills more MPG because you're always driving uphill. During one of my commutes home during a snow storm which had deposited about 3 - 4 inches on the road, my MPGs went into the upper 20s.

 

I stopped putting much stock in their reports. I saw them give wildly different marks for two pickups (different make and model) that were identical in every way except badging...made on the same assembly line. If they have a small sample size, getting a bad sample makes them think every one is just as bad when it might be an anomaly, not the norm.

 

Their 'city' rating is suspect. When I did an analysis a couple of years ago, it looked like their protocol is non-linear with either EPA or Fuelly results. They continue to hide what they do suggesting there is something dreadfully wrong ... and they may realize it.

As for highway MPG, it is consistent with my benchmarks and the EPA. But that is not what really pisses me off.

Their rating scale gives incredible preference to 'driver comfort.' I suspect a 'comfy chair' on balloon tire rollers would get a high score.

Bob Wilson

 

Bob, I give little to no credence to CSR "ratings" on a lot of items for the reasons you cited. IMHO, any rating based on subjective analysis is immediately suspect. I don't mind them adding their analysis, but I might not agree with the items they analyse or the weight they give each one. For me it's kind of like Google favoring one route over another because it's 1 minute quicker or 1 mile shorter.

I still don't understand why I can't use their city mileage when comparing one car to another. If they get 44 mpg in one and 40 in another, it doesn't matter to me if that's not a number I or the EPA can achieve as long as both cars were driven over the same course in the same manner. I get that you want them to release their testing methodology so your can validate it. But I still think knowing one vehicle gets 44 while the other gets 40 over the same course, etc., is useful data. Now, if they test one car one way and another a different way, then we have a problem, but I don't think that's the case.

 

In my analysis, I remember plotting the EPA City numbers along the X-axis and using CR numbers on the Y-axis. If the ratios where similar, then we would expect a line of some slope. This would be OK. But what I remember (i.e., suggesting a research opportunity), is the CR numbers flattened out for high MPG vehicles. So crappy MPG cars are seen by both. However, CR does something in their testing that suppresses high MPG vehicles with the exception of 'strong' EV that have the ability to aggressively capture braking energy. When 'Top Gear' proved a Prius got 17 MPG, they did it by having the driver stomp the brakes so hard that there was no effective regenerative energy capture. Hard braking appears to be a key element of CR testing.

Bob Wilson

 

I've pointed to the last page of http://web.archive.org/web/20060129105844/http://www.consumersunion.org/Oct_CR_Fuel_Economy.pdf numerous times here re: their tests vs. the pre-model year 08 EPA tests.

You can look at these for old copies of top performing vehicles in their FE tests:
Internet Archive Wayback Machine
Internet Archive Wayback Machine
Internet Archive Wayback Machine

 

Rural mail delivery likely lasts a lot longer than 16 minutes.

Per the PDF I pointed to:
"CITY MPG
Our tests. These tests are stop-and-go city-driving simulations
on our test track, which has a total of 18 stops and 4 minutes of
total idle time. Top speed is 40 mph. Two different testers each
drive three runs for a total of six 2-minute, 40-second trials on
every test vehicle. Total test time is approximately 16 minutes."

If they started off with a cold engine and ended after 16 minutes, including 4 minutes of idling, FE is going to be poor.

 

I thought about the cold engine part of this after I posted. And I can buy the idea that if the vehicles are tested as if they were being driven in New York traffic stomping the brakes then vehicles like the Prius are at a distinct disadvantage. I had been my experience though a lot of people drive short trips with a cold engine and don't baby the brakes. If there is more than 1 Prius in city traffic, I'm usually the last to get to the traffic light around Phoenix.

 

Do they know how to properly drive the prius? I didn't when I first got my used 13 and I was only getting 37mpg. Now I'm getting better at the whole thing and up to 42 and that's with heavy aftermarket 17s. Consumer reports also claims GM makes good cars, don't believe everything ya read lol.

Posted via the PriusChat mobile app.

 

The point of their tests is not to drive in a way to achieve good mileage or to hypermile. The method and speed for optimal mpg will vary depending on model of car. The point is to use the same test procedure on every car, so that the results are comparable.

Should they have done pulse and glide on Gen 2 Prius to achieve say 110 mpg (Hybrid drivers complete run for mileage mark) and report that for that car?