A tale of two Prius' - Sorry it's long

So there are a few things working against the 2.

The NiMh battery technology performs better than Li in colder climates, which is a reason often cited as to why over here in the UK they lean towards NiMh for many hybrid and electric vehicles, but Li works better when it's not cold. There are a lot of factors here, but generally speaking you'll get greater output from a NiMh battery versus Li at freezing temperature versus room temperature, and they'll charge faster, accepting a higher current. Go down to -10C / 14F and Li really starts to struggle. But that only applies to colder climates. If you're normally driving around when it's above 10C/50F then Li will nearly always perform better than NiMh.

NiMh is heaver. An equivalent battery pack weighs about 25% more than Li, and those batteries are quite heavy. A quick search on here found someone saying the Li battery is 54lbs (35lbs lighter than the NiMh).

I don't know about those specific tyres. But I can tell you from personal experience that swapping my tyres made around a 5MPG difference, so it's possible that has an impact too.

Finally there's the millage. The 2 has done 3x the distance, so it's battery will likely be more worn out.

 

what kind of damage to the doors?

THIS STANDS OUT
how are you figuring miles per tank? 280 miles would only be 6 gallons at 46mpg?
at 56, it's almost 10 gallons

tires model is important. is 32 all around the door jamb spec?

li-on doesn't help much, you can see the epa specs for both

mileage can make a little difference, but not if the car is well maintained. there are a lot of things on a 150k car that need attention, especially the engine and battery. do you know any service history?

the bttery shouldn't discharge too quickly if you're using the engine, unless going up a mountain.
it should hover near the middle in most situations except cold engine or stop and go traffic and etc.

you can get a battery health check with dr. prius

 

Also the two batteries will behave differently that you may or may not notice. With normal driving, the NiMH battery won't discharge too deeply that's because the battery has optimal life in the range of 60-80% SoC. So the hybrid ECU will keep that battery in that range of charge. The lithium battery on the other hand can handle being discharged more deeply so its operational SoC that the ECU will allow is 20-80%.

As for the tires, the stock OEM tires are Toyo Nanoenergy. These tires are really good for fuel efficiency and are low rolling resistance. The tires you have on the cars right now may not be LRR tires. This makes a huge difference in fuel efficiency. More than likely the dealership sold you the cars with whatever tires that would allow them to make a profit.

As for the mpg numbers, the car displays a number that is typically higher than what a calculated mpg would be. If you want to see what you are actually getting, do this:

1. Fill up the gas tank. Don't overfill once the nozzle clicks off. Either reset one of the trip meters now or take note of the odometer reading.
2. Drive around for a bit. The more the better because it would be more representative of your average driving.
3. Fill up the gas tank again.
4. Math time. MPG is just how many miles you drove on that tank divided by the amount of fuel you just put in the car.

You'll notice that the numbers you calculate are 5-10 mpg, at worst, lower than what the car is telling you.

Lastly, how you drive matters. If you have a lead foot, you will not be able to get really good fuel economy out of the car. If you hypermile, you can get some really great numbers.

 

yeah, there's just something completely wrong with 280 miles, have you considered the math?

how many gallons went back in?

 

maybe the gauge is off. i think the key will be how many gallons you put back in each.

 

To really know what's going on, you need to be looking at the number on the gas pump to see how many gallons you're actually putting in your tank. The dashboard fuel gauge isn't a reliable indicator of how much fuel you actually have left-- especially if it's showing "empty" when you've only used 6 gallons of your 11-gallon tank.

 

so the two has gone from 46mpg to 28mpg?

 

it does seem odd that the battery wouldn't get used more in that kind of driving.

try the same thing with the 3 and see if the battery goes down more. are you driving gently or accelerating quickly?

 

28 mpg! Wow, something is very wrong with that Two. Could be a million things-- a dragging brake, clogged fuel injectors, a bad sensor somewhere, battery issues, digital controller issues...

Hope the Toyota techs can figure it out.

 

.

 

2016 3 with 51,000 miles has a new hybrid battery?

 

What is the exact model of tires of the Bridgestones on the Two?

Have you considered doing the routine maintenance on the Two? Spark plugs, air filter, MAF/throttle body cleaning. Running a fuel additive to clean injectors and valves? Varnish and carbon deposits can affect fuel economy.

The only other thing I can suggest is that the NiMH battery on the Two is dying.