Yup, the c gets worse highway mileage than the Gen 3

The C's mileage will improve...the GenIII is broken in and the C isn't.

 

Can be a lot of factors.
1) The C gets worse mileage the faster you go, whereas it doesn't affect the full-size as badly.
2) Your tire pressures could be different.
3) Less likely, but the temperatures could have dropped only when you were driving the C.
4) Even less likely... the 2010 is dirty and is creating a golf ball dimple vortex over the car thus increasing the air flow and getting you better gas mileage...
5) You subconsciously want the bigger car to do better so you, without noticing, gave it more throttle in all situations...

Ok, I didn't say the situations were realistic.

 

The Prius C for CITY has an engine optimized for fuel efficiency in city, or more realistically stop-and-go situations. An interstate during rushhour may be more like the "city" definition than a city road with 60mph speed limit and you get all green lights.

The C has a 1.5L engine while the liftback is 1.8L. Bigger displacement engines do better on the highway where the efficiency band is up higher.

 

I agree with above posts. I have roughly 12,000 miles on my C and noticed that the C was "broken" in after about 1500 miles. My commute is 90 miles one way at highways speeds. The best MPG (calculated) was 58mpg. The only 3 variables that affect my MPG is wind direction/speed, average speed, and tire pressure. When there is no wind, I average 55mpg every day. Of course, this winter I had my Michelin XI2 snow tires on, and the MPG's really took a dump!

 

I've done a lot of highway driving with my c and the things that I found affect my mpgs are:
Speed
Wind
Outside temperature
Tire pressure
Elevation

I'm happy if I can get 46 MPG most of the time when driving around 71-74MPH.

That's probably the thing I hate most about the c - it's slow highway performance and "not so great" (40mpg) fuel economy on highway

 

I'm driving my C at about 60MPH for 16.5 miles one way here in Orange County, SoCal and getting over 60MPG easily, lot of times I got more than 70MPG and the highest was 84MPG (that was a big surprise).

 

The above poster is correct.
The "C" is for CITY.
All other things being equal...the G3 should get better mileage at 'highway' speeds.....mostly from its superior aerodynamics. The C-model is shorter than the G3.
FWIBT.

But hey...once the new year whoop-de-do dies down, you'll be able to get the trial-sized Prius for several thou less than the adult version....and the C-model will outgun almost every other four-wheeled vehicle on the interstate...and even some 2-wheeled ones.
So....no reason to hang your heads in shame or get a Scrappy-Do attitude about it.
Some drivers actually prefer the lines of the C-model, and there's no doubt that the color availability and some of the interior appointments will appear to a segment of the population that does not really identify with the G3.

Me???
I would have stuffed the G3's HSD into the Yaris platform and saved some development costs.....but I'd also attempt a 2-seat drop-top version of the same platform with maybe a user-selectable RWD/AWD.

Toyota and I are on very different wavelengths where car development is concerned, which is OK.
They're a LOT BETTER at building cars than I am.....otherwise?

I'd be building cars for a living,

 

yes, the genIII and its bigger size and design allow it to be more aerodynamic.. it helps that it has a nicer powerful 1.8L to help it chug along. whereas, the C putters around with it's puny 1.5L.

i actually find it easier for me to get better mileage on the highway than on city streets..

my commute I would say is very much over 90% highway.. and since i've owned the vehicle.. well.. you can check my signature at my fuelly banner for my fuel economy. it's not impossible to get great numbers on the highway.

 

I don't have any stick time in one, but I'll betcha the C-model is even easier to park. Most commuters are only hauling two sets of cheeks to work (requiring only one seat) and so for many road warriors it's a good fit, pun almost unintended.
The C-model is a little bit of a departure from the Priussy looking Priuses...and for some folks it's worth the one or two extra gallons you're going to burn every other tank.
YMMV...

 

People driving the C in the real world are, for the most part, getting better mileage than the liftback, so I don't think C owners are having to buy any extra gasoline.

Toyota Prius C MPG Reports | Fuelly

Toyota Prius MPG Reports | Fuelly

 

and our tanks are smaller.. lol.

 

According to Fuelly (and I believe the data for 2012 on both models)....you're right.

 

What do you mean by "slow" highway performance?

 

car struggles to get up to speed on highways - once it's there, it's okay, but getting on a short on-ramp can be tricky in busy traffic. also going up inclines on highways makes the car really work.

i wish it had more performance like the regular prius did on the highway (that car has enough power when you need it) - but it is a C after all. i hate how the regular prius handles and looks which is why we opted for the C instead

it is what it is. can't expect a miracle out of 98 hp

 

With regards to engine break-in, I don't think that the Prius (LB, C, V, PiP) mileage improves that much after break-in. In fact, I doubt that you would see anything better than a 1-2% improvement. I think that the learning factor and maintaining higher tire pressures play a much bigger role in improving average tank mpg's.

 

Owning both a 2011 Gen 3 5 Trim with 17's and a 2012 PC with factory 16's - I can definitely say that the Gen 3 destroys my PC on the highway. In town I slightly one up the Gen 3 (highest recorded 5 mile trip in the PC was 82.4, highest in the Gen 3 was 80 even).

On the highway it is no struggle to see 52-53mpg in the Gen 3 - I have only on ONE occassion witnessed 50mpg out of the c. it simply struggles to maintain speed and anything with hills destroy it for mpg. Not a big deal - i can live with my dismal high 40's on the highway

 

Just wait till the weather warms up. You'll even up a little.