Please compare Gen II and Gen III maintenance

Keeping it simple, the main difference is the Gen II has a belt and the Gen III does not. So, one less thing to maintain. Gen III uses synthetic oil, so recommended change is 10,000 instead of 5,000. I do it every 7,500. Also, the Gen III has rear brake discs, so no need to clean and adjust rear shoes... Other than that, maintenance is basically identical. The bladder in the gas tank is gone, so no trouble filling up and the thermos behind the driver's side headlight is also gone, so one less pump to worry about...

The only bad thing is the noise it makes at low speed EV. No more sneaking up on clueless people...

As far as reliability goes, I can only speak from my own experience, and that is now 44,000 trouble free miles... Good luck!

 

Second gen oil filter is a spin-on canister? On third gen you only change the paper element; it's in a reused plastic canister. When buying the paper element you also get a replacement O-ring that goes on the barrel of the canister. Placement of the O-ring can be screwed up, you should read the instructions, look at the current one. But other than that no big deal. You need an oil filter socket with 64 mm inside face-to-face, 14 flutes. Don't cheap out, get a sturdy one. The Honda filter I have works perfectly, btw.

One serious "gotcha" with the paper element, it is VERY easy to forget to put the new paper element in. Once everything is buttoned up, it's impossible to tell. I've just about missed it myself. And there was a member here, when he did his first DIY oil change, after dealership service, discovered he had no filter element in there.

Second gen doesn't have an engine underpanel? Third gen does. It has a "flap" at the oil pan location, that theoretically could be bent back for access. Problem is, it really doesn't want to bend, and owners that have been doing that are seeing that flap break off. Personally I'm the only one doing my oil changes, and I've opted to remove the whole panel for oil changes. The two fasteners at that flap are larger than the rest, grey coloured (at least on mine), so you want to be sure to not mix them. Also, wash out any fasteners when they're off, get the grit out.

Second gen transaxle has different drain and fill bolts? Third gen they're both socket head cap screws with 10 mm hex socket.

If you're going to be raising the front end and supporting it on safety stands, I'd comment: the scissor jack support points on the rocker panel are very poor for safety stand placement. They're not reinforced, it's akin to supporting the car on knife edges. I place my safety stands at front end of the main underbody rails, just in and over a bit. At the rear, there's a similar (albeit not so extreme) situation, and again there's an underbody reinforced zone that's better for the safety stands. If you're interested I can post some pics.

The third gen has gone to disc brakes on the rear. While braking performance has likely improved as a result, rear disc brakes are kinda finicky; there's always a need to incorporate the parking brake. Toyota's iteration requires very careful attention when reassembling: the orientation of the caliper piston face in relation to a pin on the back of the inner pad is crucial (see attached).

 

I guess the (electric) engine coolant pump on the gen 3 isn't susceptible to leaks like the (belt-driven) one on the Gen II can be.

 

Many gen2 engine water pump leaks are caused by belt being too tight. It’s causing pump bearings to wear and seal to be under extra stress.
With electric pump you don’t have that problem.