Hard to believe an air filter could have that much dust in it by 38k miles, but it did. First, I wasn't expecting the air filter to be so small. Second, it was one of the easier modern air filters to pull out and put back in. Out of curiosity I took it out and tapped it on the concrete sidewalk. I was shocked at how much dust came out of it. So I tapped it a bunch until the dust seemed to be lessening for each tap, then re-installed it. I wasn't expecting to change it out, so I didn't have one with me. Now that I have seen how small the damned thing is, and how dirty it was, I will probably be replacing it with an OEM one again. But the car's pick-up and go for highway merging and highway passing got a boost from it. I'm not sure what the change-out interval is on the air filters for Gen4's, but 38,700 was about the limit apparently.
Mambo, Your Prius keeps track of the battery temperature and cuts back the use of the battery as the battery temperature rises. This is to protect the battery from getting too hot. Since the battery supplies power for acceleration to aid the puny ICE, performance suffers if the cooling air flow is cut down by a clogged filter. JeffD
IMHO, 38,000 between engine air filter changes is WAY too long...for what they cost and the ease of swapping them out, at a minimum, every 2-years. (For cabin air filters, I use the charcoal activated ones so they only last a year.) A dirty filter means your MAF sensor and throttle body is probably in need of being cleaned as well, easy DIY projects. It's best just to check the ICE air filter when you do an oil change. Toyota OEMs are white for the Prius so it's super easy to see if they are dirty.
I was thinking engine filter right away, from the OP. Think it "depends". Our west coast location is maybe less dusty., compared to more inland. I finally changed both cabin and engine filter at 88K kms, after approx 10 years ownership. The cabin filter looked deserving of replacement, but the engine filter looked nearly new still. Figured change them both once and be done.
Air filters have air flow directions on them. As the air flow through the filter, it filters bigger particles first and as the air flow through the filter media it filters smaller and smaller particles. It may not look dust on the outside, but the inside could be clogged with smaller particles.
It's also going to depend on drivers who use the gasoline engine assist more - like me with an average of 40 MPG - vs. someone who gets 50 or 60 MPG. Drive it easy, especially in an area that doesn't require the air conditioning nearly every day, and that owner will have a less clogged engine air filter than another Prius driver in the same road conditions (like me, for example) who has the engine running most of the time. This is the first time I've ever ordered an OEM air filter, but I trust Toyota. So much so that I will probably not buy any more Mobil 1 oil filters for it, and instead buy Toyota oil filters while still using Mobil 1 0W-20.
Replaced my engine (and unrelated - but also cabin air) filter a month or so ago at 34k km. The engine filter was OEM - couldn't tell you if it was original 2016, or replaced at some point at least, but oh boy. It wasn't the worst air filter I've seen, but it was time to go. Can't tell you that I've noticed a bump in performance or MPGs - probably marginal at best, but given the cost and ease of doing it yourself, there's really no reason not to do it fairly frequently. On a conventional car, you'd do it every year or so - maybe on a Prius you can get away with it being a bit less frequent. But yeah, definitely didn't expect it to be that small. I do appreciate the ease of access though.
So I was kind of surprised when you wrote that they were white. Mine was anything but white, and seemed to be a natural yellow color (as some other brands of air filters are). The new one showed up today, and wow! White!
