What all goes wrong as a v gets high mileage?

I’ve got a 2017 Prius with around 350,000 miles on it. I’ve been driving it about 3 hours a day since it was new, and here’s the maintenance history so far:

• Replaced the brake pads twice.
• Replaced the left rear wheel bearing assembly twice and the right rear bearing once.
• Recently had to replace the water pump after it failed about 3 months ago.
• Reconditioned the hybrid battery 4 months ago using a 4-channel RC battery charger. It’s been working fine since, but if it fails again, I’ll probably just buy a refurbished one to save time.
• Earlier this year, I replaced the spark plugs and coil packs, likely because they were fouled by a coolant leak.

Speaking of the coolant leak, I’ve been adding about 8 oz +/- of coolant daily. There’s no coolant in the oil, but an exhaust gas test shows exhaust gases in the coolant tank. I suspect the EGR cooler might be the culprit, but the head gasket is probably on its last legs, too. I plan to replace both soon, along with the timing chain.

Other upcoming repairs include replacing the right front control arm and both ball joints.

This car has definitely been through a lot, but it’s still running strong for now!

 

This is a 4th gen Prius, not a Prius v, which ostensibly is a gen 3, with the same engine and EGR system? I was kinda wondering why your laundry list did not include occasional EGR cleanouts, and/or head gasket replacement.

 

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I never had a problem with egr. I assume because it's mostly highway miles. never had an issue with egr. I've done all the work myself to save money. if it isnt broke or throwing a code it isn't fixed. this will be my first headgasket replacement. as a. correction I have 301000 miles not 380 as I stated above.

 

Your egr cooler has to be totally plugged