I just bought a 2010 salvage Prius. I have another 2010 I have been driving for 3 years so I am pretty used to the mileage I can expect under different conditions. When the car is totally warm and I measure the mileage for 15 miles or so I get normal readings of mpg. But with a lot of 2-3 mile trips during the week I am getting about 10 mpg less than usual compared to my other 2010. I have been too busy to look into it in the last week, but now I am ready for help. Suggestions wanted. Thank you, Barry
When the Prius stars 'cold' it's primary focus is getting the Air pollution controls up to temperature. It only focuses on mileage once warm. So grouping trips to stay warm, really helps Grill blocking and Engine Block Heater can help when it is really cold out.
My Prius is a turd plopping dog in the mpg department when its in the warm up period. But, on another note, what are your tire pressures at? If it was a salvage Prius, was it in a major crash and are all of the underbody wind deflectors in place, etc?
as a clue for us detectives, what are the long trip mpg's, and what are the short trip mpg's for each car?
The 2010 I have been driving for 3 years is getting about 48 on short trips, 56 when warm. In both cases driven for optimal mpg. This is a level 2 package. The salvage 2010 is getting 38-40 mpg on short trips, and 56-57 when warm. I raised the tire pressure to 34 from 32 psi a week ago, no help. The wreck was pretty minor, head on, front bumper, and both head lights, the hood is original and the airbags never activated. It happens to be a level 5 Prius, with the lane following and adaptive cruse control, but no solar roof fan feature. The heat seats are turned off during these mpg measurements. And I have left the heater off during these measurements. I am suspicious that the 12 volt battery may have been discharge while the repair work was done. But could that cause this big a problem with warmup mpg? I am not sure about this next piece of info. I think I saw 4-5 bars on the battery when I parked the car at the end of the day but then only 2 bars when I started it the next morning. This was in the first couple of days after getting the car, but I don't think I've seen it again. Barry
The consensus here is when the 12 V battery has been through a deep discharge, it's life is on borrowed time. It also can cause a reduction in MPG due to the engine having to run more than it normally would. You could always stick a battery charger on it overnight and see if it helps. Or have the battery checked.
Yes, it has 17" wheels. I just measure the battery voltage. It was 12.43. With an 8.6 ohm load it dropped to 12.15. Should I leave the load on for some period of time?
Wheels will make a big difference in mpg maybe 3-5 mpg, also check PSI on side of tire you might want to increase PSI a little bit. Do not go above max side wall posted PSI. I'm no battery expert someone else will chime in I'm sure.
it's the difference in short trips that's baffling. it's like damage from the accident is causing it to warm up more slowly. i don't think the gen III has a coolant thermos, but is has exhaust coolant warming?
Yes, I agree. Makes me think there may be some temperature sensor or valve it controls (or the two combined in some sort of flutter valve) is not allowing the exhaust to warm the engine. The warm up reminds me of my 2001 which I just sold. I have been very impressed with the very fast warmup of my 2010 level 2 package. But I am an area of CA where the night temps are only under 32 4-6 times a year.
Maybe Toyota has a way to run a scan on the exhaust coolant warming system to see if it is operating properly!
A difference of 8-10mpg cold is significant. IMO 34psi in a tire rated at 51psi is too low. I'd buy a couple mpg for the tires & a couple mpg for the tp but I'd expect an effect on the hot number as well. A weak 12v battery would also affect both hot & cold numbers. EGR valve?
The battery with a resting voltage of 12.43 is somewhere between 50-75% the capacity of a new battery. It should be ok, my car's battery is at 12.2V and i get better than that. When i bought my car i remember reading an article with quotes from a toyota engineer explaining the warm up time on the gen3 is much quicker because it does recirculate the exhaust in such a way as to get everything warmed up. The time dropped significantly from 10minutes to 4 minutes. I would hook up an OBDII adapter with the torque app and log your engine temp over time. You have the benefit of 2 vehicles, so you can compare. Actually i found a link to a similar article: Tirekicking Today: 2010 Toyota Prius So essentially the exhaust probably controls some sort of valve for running coolant around or running exhaust through a heat exhanger to speed up warm up time. If said valve was unplugged, wiring cut, or damaged and inoperable. Your warmup time would be like a gen 2.
