What Prius should I sell? 2010 IV or 2006 Package 8?

I'd sell the older higher mileage one. (2006 w/ 134K)

 

The biggest risk in the gen 3 is a blown head gasket at 130,000+ miles. Many forum members have fount the EGR circuit, especially the EGR cooler, to get clogged which may contribute to the head gasket problem.

So, you are probably OK for another 50,000 miles but then, if you can do it yourself, cleaning the EGR circuit would most likely keep you going after that.

It is also common for gen 3 to start using some oil eventually but that is not a problem if you check it regularly.

then there is the risk of hybrid battery failure eventually from age, not miles.

 

Take the modules out of the new pack and swap them into the g3 before selling the g2.

Actually, this is what I would do since I, too, drive low miles per year (about 8k): I'd sell both and get a plug-in with the cash.

 

160k on mine, 66.0 mpg for the last 5,120 miles. My engine is over 150k so I’m in big trouble

 

Easy, Sell hers because you won’t have anything to drive if you sell yours.

 

Assuming both cars are in comparable shape and have been maintained properly, my biggest concern with the older car would have been the battery since it's now 15 years old. But you've addressed that, so I'd keep the '06 and sell the '10.

The Gen-3s seem to have more trouble spots: head gasket, oil burning, brake booster, inverter (the last two are covered under extended warrantee until next year, but after that I think you're on your own)
I'm not aware of any problems like that with the Gen-2.

I'll put it this way: My daughter will graduate from college in about a year. Now she has a perfectly fine "college car": inexpensive, mechanically sound, a little rough around the edges, but reliable. When she gets her first job, I presume she'll be ready to upgrade. She really likes my wife's '13 Prius V Wagon and liked our '08 Prius hatchback when we had it. When she asks my advice, I will HIGHLY recommend that she not get a Gen-3 Prius. If she were considering the two vehicles you are, I'd recommend the '06.

 

I'm always worried about the expense of putting in a factory hybrid battery. The '06 should be good for another 10 years- based on the cost, I'm assuming it was dealer installed. If I'm mistaken then disregard this post.

The '10 just had its traction battery's warranty expire. If the '06 is running very well then I'd keep that. Based on the posts here, the '10 seems to be the gen3's worst year for engine issues.

 

Edit after seeing the last post:
Good job on the decision to keep the 06 and sell the 10!
Since you've already took care of the battery on the 06, this car will no doubt be more reliable than that 10.

This is taken from my experience with my mom's 08 I've maintained for the past 7 years in comparison to my 10 that I've owned for the past 2+ years and the amount of times I've spent fixing my 10 vs working on the 08..AND the upcoming engine swap I have to do on the 10....yeah keep your Gen2 if you want a more stress free ownership experience for the next 5-10 years or so

 

The '06 has a new battery? Sell the 2010!

Always dump the one with the oldest battery.