Gen 4's a lot better in quite a few regards...
-stealth mode below 10-15mph
My Gen 4 will very easily go into stealth mode at 40 mph, will sometimes do it on a level highway at 60 mph, and it'll even do it on downhills at as high as 73 mph.
Mine could use more lumbar support, but other than that, I find the Gen 4's to be quite good. Not quite Volkswagen good, but good, and heavily bolstered. (I'll get to why that's important.)
-attempting to take off quickly from a stop and the traction control cutting all power. This issue bothered me a lot! I remember many times trying to pull out in traffic quickly and power cutting out - hopefully they re engineered this one for safety's sake.
Low rolling resistance tires are better nowadays, the traction control doesn't seem to be ridiculously aggressive, and there's now a traction control off button.
But after selling the car and getting a Jetta Sportwagen with a growing family, I realized just how much I missed having a "driver's car". By that I mean something that handles well, has some power/braking and feels connected to the road. I hadn't realized it, but the Prius had pretty much numbed me to the driving experience. And I totally get how some people could care less about a sporty car, but I can't see myself going back to a Prius.
Test drive a Gen 4 if you need to replace your SportWagen - I find that (compared to the couple of Gen 3s I've driven), they've greatly improved the steering feel and steering rack speed (and it's actually
good in those regards), and the handling's actually fairly responsive. The vehicle actually likes to rotate more, the more you push it, interestingly.
Now, the braking still feels weird as it tries to figure out friction vs. regenerative braking, and it's not as direct as a manual transmission vehicle, but the powertrain is decently responsive in mine - I'd say that typically, if I put my foot down, there's less lag in getting the power than there is in an ALH with a VNT15. (And, it'll be more powerful than your Gen 2 was. Still, slower than a common rail TDI. Edmunds got 8.9 0-60 without rollout, 8.6 with, in a 2010 JSW DSG. Compare to 10.1 without, 9.8 with, traction control off, for a Prius Four Touring. Lower trims will be faster, especially Two Eco.)
I've since come to the conclusion that biking/pedestrian centered life is central to sustaining the planet and our health, so I've made life decisions around that.
Yeah, that's ultimately the direction we need to go somehow...
This comparison between the Prius and the TDI is a bit silly to me. You're comparing a gasoline-electric hybrid to a pure diesel. There is no technical reason you can't have a diesel-electric hybrid and get the sky high fuel economy that comes along with it. As far as I know only the only mass production diesel-electric hybrid was a Mercedes E class in Europe. There was talk of a TDI hybrid back in 2008 but I don't know if that went anywhere.
Sure, there's no technical reason why you can't do it, and there's diesel-electric hybrid buses allover the place, the aforementioned Mercedes, as well as a few Peugeot and Citroën diesel-electric hybrids (that didn't actually work well as I understand). However, there's various reasons why it doesn't happen in practice.
The first is simply... a diesel engine with all of its emissions controls (including, now, AdBlue) is expensive, difficult to package cleanly, and adds weight.. A hybrid is expensive, difficult to package cleanly, and adds weight. Now you have to pay both the hybrid
and the diesel price premiums, package both ~1 kWh of battery
and the urea tank, and deal with a rather heavy car.
Then, there's the benefit that the system provides, which is diminished with a diesel.
So, a hybrid system's first obvious benefit is that it can do regenerative braking, and then use that power to get off the line, and that is absolutely present on a diesel hybrid.
A hybrid system in the form of the Toyota/Ford system, or the GM 2-mode system, can also provide a very effective form of simulated CVT, with almost instant changes between ratios, more efficiency than a true CVT, and (at least in the case of the designs that Toyota and Ford use) better reliability than any other type of automatic transmission (I'd actually argue better reliability than a manual, too - nothing's designed to wear out in the Toyota and Ford systems), and better smoothness than anything else that isn't a CVT (no shift shock ever, it just gets to the perfect engine RPM for your power demand and stays there). That obviously helps a diesel, too. (Which is why there's a ton of buses running around with Cummins ISBs and GM 2-mode transmissions...)
However, neither of those are fundamentally rethinking the engine connected to the transmission, relative to the benefits the hybrid system gives.
Naturally aspirated gasoline engines tend to be lacking in low-end torque compared to turbodiesels of similar displacement... but the electric motor can help fill that in. On a diesel, you may well end up traction limited. (Granted, you can just use less diesel power, but high load at low RPM is the most efficient point usually, meaning you may have to avoid that most efficient point altogether, or not use electric during your acceleration, only cruise. On a diesel, not the end of the world, part-load efficiency is good too, but you're leaving some fuel economy on the table somewhere, most likely.)
This also leads into the Atkinson (or possibly more correctly, Miller - although that is usually used to refer to a supercharged motor with retarded intake timing) cycle combined with an increase in static compression, which greatly increases the thermal efficiency of the engine by getting more expansion out of each combustion event, without increasing actual compression and getting the thermal losses and detonation of that (because some of the excess air is getting pushed back out). For diesels it gets trickier to implement because the static compression needs to be extremely high, but it's relatively easy (especially with modern ECUs, to handle the intake reversion) to implement on a gasser. It does hurt low-end torque, though, which... that's what the electric motor is for. The upshot is that my Prius has a 40% thermally efficient engine (compare to 42.5% efficient for the ALH or the CBEA - and that CBEA figure is probably while cheating) in most operating regimes, with port injection, intake cam only (IIRC) VVT, (heavy) EGR, and a three-way cat. (There is also an exhaust heat exchanger, to speed warm-up.) So, the hybrid system enables gasoline engines with near-diesel efficiency to be used. And, with such an understressed engine (96 hp, 104 lb-ft, out of a 1.8 liter), it can be rather light, too.
Gasoline engines (that aren't set up for lean burn, anyway, and for emissions reasons that isn't a thing any more) tend to have very poor part-load efficiency. A hybrid system can prevent the gasoline engine from ever seeing partial load, by harvesting electricity off the engine if the power demand is lower than the minimum full-load power from the engine. Charge the battery, then once you're at a certain state of charge, shut down the engine and run on electric alone. Repeat as needed. A diesel doesn't get helped by this as much, because of the vastly improved part-load efficiency enabled by always lean burning. (This is also why downsizing and turbocharging gasoline engines is so popular now - the goal being to improve the range of efficiency. The problem with them is that, while at full no-boost load, or a little bit of boost, they're rather efficient (and they'll be there during a cruise usually), but to avoid detonation, they have to run very rich, and as a result are inefficient during acceleration. So, the range of efficiency isn't improved, it's just that the efficiency that's there is available only at part-load, not at full-load. And, this is also why Mazda has things like their wide-authority VVT system on gas engines - full-load is done at Otto cycle, but part-load is done in an Atkinson cycle, by retarding the intake cam on the fly - in the real world, that actually works rather well, because it's no worse than the old engines that it replaced at high power outputs (unlike turbo motors), but low loads are efficient too.)
Basically, you can do a diesel hybrid, but a couple of the effects that it has for making a gasoline engine operate more efficiently while being drivable don't apply to a diesel really, so you won't get the kind of gains that a gasser gets from it, and you get all of the drawbacks in cost, weight, and packaging. A diesel hybrid almost entirely helps you in the city, a gasser hybrid helps you everywhere relative to the base engine.
Another way to look at it is, rather than looking at things at a technical level, ignoring that you can't buy a new TDI... "I've got about $25-30k to spend, I want to get good mileage, what's the best way to do this?" A 2015 Golf or Jetta TDI, or a 2016 Prius will get the same ballpark of highway mileage, and once the TDI isn't cheating, the Prius will get better mileage most likely (but the Prius will do it on cheaper fuel), the Prius will get
far better city mileage even with the TDI cheating, the Prius will have more space (more like the Jetta sedan, maybe even more than that), the Prius weighs less than either a Mk7 Golf TDI DSG (and most trims less than the manual) or a 2015 Jetta TDI (either transmission), and the Prius has a better transmission than the DSG (I'm not gonna say it's better than a manual, that's a preference). Oh, and the Prius is less likely to break in expensive ways...