I avg 38mpg on my 2005 prius.

The Prius is sensitive to tire pressures. If you havent checked in a while, I would make that a priority.

Also, most members inflate their tires to 44 or 42psi in the fronts, and 40 or 42 in the rears. This is done at your own risk but is beneficial for fuel economy.

 

It's correct to use the AC to get a comfortable cabin temperature, as the cabin air also provides cooling for the HV battery.

You may however find you can get sufficient cooling without having the AC on full blast. The Prius AC has variable output so it's not a case of all or nothing, and you can adjust both thermostat setting and the fan speed. Personally I find I'm usually comfortable enough with the temperature set point relatively high, like about 25.5 to 26 C (78F), and the fan speed low to medium. Just the dehumidifying effect of the AC really helps as we have very humid heat here. These AC settings make quite a big difference to MPG in my case.

Could be ok, depends on when it was measured. If measured as instructed, after letting the Prius sit (off) for at least a few hours (pref overnight), then it's ok but just a little bit weak. If it was measured immediately after driving the car (or having it "ready" for some period of time) then the true results could be significantly lower than what's indicated.

 

The things that really jump out at me are:

Checking tire pressure is essential, don't let this item escape.

Full blast max cold AC will clobber your mpg, especially in city traffic where you spend a lot of time sitting without rolling up miles. If mpg is important, turn down the fan and turn up the temperature as much as practical. Otherwise, just write off the mpg as a cost of keeping yourself and the gf comfortable and happy.

As another reply already mentioned, hard braking defeats the effectiveness of regeneration. When you need it, you really need it. But most of the time you should be able to plan far enough ahead to use light or moderate braking and get much more out of the regeneration.

 

Concerning your driving style, your braking is probably only part of the problem. Barely pressing the gas can be almost as bad as hammering on it. You need to find the happy medium that makes the engine work a little. I find that having no arrows to or from the battery during acceleration is best, having it going back and forth between no arrows and arrows is also close enough. Accelerating with just electric should be avoided unless you're in a parking lot or stop and go traffic. I also pulse and glide or use cruise control when traffic permits. Its very easy to have the pedal pushed just a little more than it needs to be and it can drag down your mileage.

I would bump up the tire pressure to at least 38-40PSI (I personally do sidewall max, but some people find it too rough). Your alignment could be out of whack and your 12v battery could be on its last legs, but I would hold off them until you've tried a few free/cheap tips. Running the AC at full blast in the city will really tax the HV battery. Using auto AC and setting the temperature at 72 or higher should keep you just as cool without making the compressor have to work as hard. There are many posts here and on other sites about driving the Prius efficiently. Even if you only apply some of the techniques, you should be able to average at least 45MPG.

 

A/C on all the time, full blast, max cold would be uncomfortable in my car. Perhaps the OP's A/C is not working to its optimum capacity. Check the sight gauge for charge level.

 

It is a little glass window on the compressed AC refrigerant line, allowing you to see the fluid flowing by. The amount of bubbling gives a hint to whether the system well charged or depleted.

I can't say if my Prius even has it. Some of my past cars had it, some did not.

 

If the AC at full blast and max cold isn't freezing you, there could be something wrong. Check the cabin air filter to make sure it isn't clogged. If its ok, you might want to have the dealer check it out.

 

I guess people call it sight glass more often. Here is a thread that has videos down a bit:
PLEASE HELP!! - 2005 Prius A/C Evaporator Problems | PriusChat

 

Those are some significant symptoms. A/C working poorly, and making grinding noises, sounds like you are needing to get some professional help. The compressor would appear to be on its last legs.

 

I would probably look at compressor and ICE motor mounts.

 

Some part of your problem may well be a old 12 volt battery. 11.anything is awful low.

 

Jimbo, above is what the OP posted for the 12volt. See post#10 in the string. I do agree it is weak.