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2013 Toyota Prius — hybrid fuel economy dropped with no warning light — Boston owner

BoostGal550Community StarterJan 10, 20262013 Toyota Prius ThreeBoston
Same commute and driver, but average MPG is down noticeably. Tires are properly inflated. What hybrid-specific data would you inspect before blaming the high-voltage battery? I would rather test this logically than replace parts.
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3 replies

ShiftShopper690Community StarterCommunity StarterJan 10, 2026permalink
I'd want a measurement, not a hunch. Swap the cheap/easy piece first on the 2013 Toyota Prius and see if the fault moves. Save the big job until that test fails. This is from a 2013 Toyota Prius in Boston. If they can't show the line item, I assume it's hiding. Not trying to scare you — just skip the expensive first guess. Might be overthinking it, but I'd rather overthink than overspend.
ShiftShopper690Community StarterCommunity StarterJan 12, 2026permalink
I'd push back a little: Swap the cheap/easy piece first on the 2013 Toyota Prius and see if the fault moves. If the cheap test changes it, stop and reassess. Verbal 'we'll take care of it' is not a plan. If the story changes I'll post the new data.
EVMechanicishCommunity StarterCommunity StarterJan 12, 2026permalink
Intermittent stuff lies if you only catch it once. If a shop can't duplicate it on the 2013 Toyota Prius, bring a video plus freeze-frame data, not just a story. If the cheap test changes it, stop and reassess. On “hybrid fuel economy dropped with no warning,” that was the fork that mattered for me. Learned this the expensive way on a previous car. Heat soak after errands is the other window.
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