Sell, or not to sell.

If finances are the only consideration, then it almost never makes sense to turn in an older trouble-free car and replace it with something newer.

Wanting upgrades dramatically changes the situation. If you want upgrades, while still making financial sense, then you'll have to decide how much value each of those upgrades is worth to you now, vs delaying them a while or possibly indefinitely. Then roll in your ability to afford those upgrades, vs your other financial plans.

I kept one car 23 years. It wasn't trouble free, but the troubles it had were still cheaper than depreciation on a new replacement even at the end, when I decided that I really wanted to upgrade to something with airbags and ABS and better crash protection and modern fuel economy. That is when I got my first Prius. But I kept that one only 3 years before deciding I wanted to upgrade to a higher trim level, and easily could afford to do so. (It also helped that it traded in as just a 2 year old car, not 3 years old.) Now that one is approaching 9 years old, and I'm looking at replacing it with a PHEV, once the right thing/deal (Prius Prime has a couple shortcomings from our needs) becomes available.

Spouse's daily driver is 32 years old, first owner. It is now dirt cheap to own and maintain and renew registration and insure, and still fills her needs. I haven't been able to talk her into upgrading to something with airbags, ABS, side impact protection, ...

 

I was in a similar position a couple of years back when I upgraded from our old 2010 Prius II with 200k miles on it to our 2019 Prime Plus.

I had done all the preventative maintenance in our old 2010, but when you get the itch to upgrade and something comes along that pushes you over the edge, go for it.

In my case, @Pedal Logic had a friend who had a need for reliable transportation but was in a spot, so I helped out. Didn't take much pushing and we came to an agreeable sale price.

 

I got a 2003 Nissan Sentra XE in 2007 with 51k miles on it. I ran it until 2017 when I swapped it for a 2014 Hyundai Elantra. Then 14 months later I swapped that for a 2016 Ford Fiesta, then 5 months later swapped that for my Prius C2. This Prius was well maintained and has been a perfect used car. I see no reason why I shouldn't run it until it's at least 20 years old in 2032.
I wish I'd ran the Sentra until 2023. It was a nicer car when I traded it in in 2017 that it was when I bought it in 2007 and I only put 40k miles on it in those 10 years. That was the longest I'd ever had a car. It was a nice car.

 

Same boat here.

I've got my eye on the Rivian.

I'm looking forward about 4 years for the purchase, so time will tell.

 

financially, run that prius c to the ground (or until you need to replace something that just costs too much...more than it's worth)

if you're to YOLO, I wouldn't do it on another Prius

 

@bonanzoo, How did you change the brake fluid? Do you need to put the car in "invalid" mode? Could you please share the steps? Thanks.