"If the used part is a bad idea, then is it completely crazy to spend $4,200 on an 8-year-old car??"
What scares me about this hybrid technology is that it is maintained by the same people that screw up our regular cars.
The stuff is treated like a black box because it may not be serviceable to component level. Even if you could go in and change just certain parts of the assembly, mechanics don’t know about electronics so can’t waste their time troubleshooting it. You swap things in and out because it is expedient and profitable.
Couple that fact with the other tid-bit that some of these guys are not the sharpest knives in the drawer:
Just this week we had mechanics start a car fire when changing a battery, a dealer suggest they replace an ECM and ignitor to see ‘whether it fixes the issue’, etc. Some of these guys are horrible.
There are some really good ones but there are also very bad and dishonest ones. Not knowing who is good and who is bad, I wouldn’t blindly trust their judgment and get a second opinion. Not doing so would be like opening you wallet and saying “Take what you want”.
Of course, dealers are the only game in town when it comes to hybrids. You’re stuck between a rock and another rock.
Since you can’t get a second opinion by an independent, I wouldn’t spend 4200 bucks on an 8 year old car but would also not get a hybrid.
Totally agree with @TwinTurbo, btw.