Prius Millage Dropped Drastically

first, i would speak to the person who replaced the part, and tell them your concerns.

second, i would drive it for awhile to see what kind of mileage you're getting. how many miles/km have you driven, noting the higher fuel usage?

third, why was the part/rod replaced?

 

As far as HV health, you should be able to charge the battery all the way up by force charging. Start car, put foot on brake, set foot brake, put car in drive, watch HV Battery charge on screen. If it doesn't you have a real problem! Take it to a shop.
Most people put their location, this helps determining and solving problems. For instance, should you be close to a desert, sand could be a interfering component, you may want to put in a new air filter post haste. Heat is also negative.
Checking wheels: easy to do, pretend your changing a tire, and spin the wheel or turn car on and put in drive and listen.
IF YOU HAVE NEVER CHANGED A TIRE, DISREGARD THE LAST PARAGRAPH TOTALLY
Get some help. Easiest thing to do is to take it to a Toyota Dealer. That thing between your wheels may be the tie rod, if it's damaged you may need a new one.
Please tell us something about yourself like a nickname, what town, age, buy car new? Miles on car etc. Thank You. WARNING: DO NOT DO CHARGING PROCEDURE IF YOU FEEL NERVOUS ABOUT IT. Remember the brakes ALWAYS override, overpower the engine.
Good Luck.

 

I hadn't noticed before, your speaking in terms of engine consumption on liters. Also convert to mpg and PCers would understand it better. Engine fuel consumption is a separate subject. EV CHARGE RELATES TO RANGE.

 

Do you realize you are on the Prius C forum? What model do you have?

 

Have you inspected the brakes? Is one brake hotter than the others?

Is the ground wire from the 12v battery securely attached to the rear of the car?

 

Moderators will likely move your posting to the regular 3rd gen maintenance and troubleshooting forum, no big deal.

Your mileage change, converted:

21 liters per km: 49 mpg (US gallon)
14 liters per km: 33 mpg

Regarding your questions:

1- Can I check if my Hybrid battery is getting weak or what is the health of my hybrid battery ? If yes then let me know how.

There is a diagnostic regiment the dealerships can do. Toyota UK has started officially offering it. Not sure what you can do in your part of the world, but if you show the link to any Toyota dealership, that might get the ball rolling. They call it "hybrid health check":

Hybrid Cars Health Check | Toyota UK

How long was the car in the shop, and was it due to an accident. A protracted idle time in a repair shop might have degraded the hybrid battery, or not. Even more likely is that it weakened the 12 volt battery.

2- Is there any way if I can check my front tires are revolving without any friction and revolving freely ?

Yes, feel the middle of both front wheels after a drive. Actually, check the rear wheels similarly. If the wheel is cool to the touch or only slightly warm that's ok. If it's quite hot, the brakes are likely dragging.

 

maybe they left it idling a lot and you only think your mpg's have declined.

 

Without a proper summation, history, it's difficult to guess anything. I don't think I even read that the car has been to the dealer for any kind of service........?

Sounds nice.

 

Ahh, Progress. I presume NO Toyota Dealer?

 

Your speaking of the -12V lead going to chassis ground? With that loose, that could be a catastrophe , might as well look at +12 v also, even more problematic .

 

I kind of doubt it's your hybrid battery.
It's only 5 years old, and if it was really failing I think you'd see other signs or codes.

I hate to say it, but I'd check your 12 volt battery. If it's the original, it's old enough to be in the failing range.
Otherwise, of course I'm suspicious of the repair you just had done. BUT if all the feedback is that it's fine?

I'd check the 12 volt battery as a starting point.

 

He hasn't clarified his Mechanic yet.

 

someone replaced a rod thingy between the tranny and the front wheel.

 

I will answer inn terms that you are a DIY ( do it yourself )

1. So you have some drag, either physical or electrical
2. As long as the battery is reading 12V + it's OK, do you have a multimeter?
3. Sorry about that
4 Glad to meet you Talha , Welcome to Priuschat
5 just letting you know that if you have the car in drive and your foot on the brake with the other foot on the accelerator, FULL, the braking system predominates and the car will not move.

My only suggestion is to look at the last place(s) the car was worked on and recheck everything. Take no ones word for anything ! Example: your mechanic said the wheels are OK.. You must jack up every wheel and see that it spins freely.

The other option is to totally trust your Mechanic and visit him often for the same problem, over and over again.

Hope this helps. Most Sincerely, Andyprius.