Noticing how wind effects mpg's on my C.

Yup. Wind and load will affect mileage drastically. I also try to keep the AC off when possible. (sorry- I live in a hot place).
Also- external temps also affect performance.
Prius likes warm weather- which makes it perfect for us!

 

You may want to measure any elevation differences on your usual route to and from work. Sometimes the difference is minor but very much affects mpg. I use an app called MyTracks to measure elevation while driving. It creates a nice little graph for you. This is one of the things I usually recommend people do to determine why their mpg is different from other Prius owners.

Here is my commute graphed out. Multiply elevation by 10. So it is a max of 1,200ft.

 

You're doing great.

The Prius is very susceptible to high winds but the mpg loss affects all vehicles. The difference is the Prius gets such high mpg numbers that when you lose say 10% due to wind or rain, the resulting loss looks large because of the numbers involved. 10% off 50 mpg equals 45mpg which is a 5mpg loss. The same 10% loss at 20mpg equals 18mpg which is a 2mpg loss. The 50mpg car appears to have lost more but in reality the 20mpg car is using more fuel.

 

I'd claim that the apparent numeric impact is much worse that. In nominal conditions, Prius uses 60% less fuel than a 20mpg car. But its cross section is not 60% less, so the proportioning method here won't work.

I prefer the gallonage method. A 20 mpg that hits winds strong enough to drop its mpg to 18 is using an extra 0.56 gallon per 100 miles. If the wind causes the same extra fuel consumption in a Prius, its mpg will drop from 50 to 39. If it can instead eak out 40 mpg in the same wind, it is actually doing better than the 20->18 mpg car, despite what appears to be a disproportionately large change in mpg.

 

Your Prius may like warm weather, but the Traction (HV) Battery hates being hot. Elevated temperature significantly reduces HV battery service life. You should run the AC in hot weather as the cabin air flows over the HV battery to keep it cool.

JeffD

 

I've had my C since July, but I've put almost 9k miles on it since then. This week my MPG has dropped by 5-10. It also got cold...does that sound normal or should I get it checked out? I've never owned a hybrid before so this is all a bit new to me.

thanks

 

Why mileage gets worse in winter | PriusChat

 

Thank you! I'll be trying this suggestion and perhaps the grill blocking:

"Better heater management (more details at Which one?): if you're using the heater and while stopped, you find that the ICE (internal combustion engine) seems to run or start up "unnecessarily" when the HV battery doesn't appear "low", do this:
- stop using auto mode on the HVAC system"

This is exactly what I was noticing--the ICE has been running constantly all week. Thanks again!

-B

 

I never use the auto mode either. Also kept the air on most of my 5,000 miles. By keeping the temp around 72 or 74 and running fan on low I see little difference with air on and air off.
I run a 26 mile trip twice a week, one way. Get mid 40's going west and upper 50's heading east. Road is flat, I watch the altitude on my gps. Best I can tell, there is a little wind daily blowing from the west. I also noticed this same thing on our Vibe gt, using the ScanGauge. May also have something to do with the surface of the road being a little different on east and westbound lanes. Not just sure but I know there is a noticable difference.
Dan