According to this article: Green Car Congress: Prius c hybrid goes on sale in US with entry MSRP of $18,950; new transaxle, motor technology Sounds like Prius gen 3 transaxle (p410) should be more resistant to stator coil shorts compared to gen 2, but less so compared to Prius C transaxle (p510). Here is the relevant text:
The major transaxle stator improvements came with the NHW20 over the NHW11. Only the NHW11 has shown a measurable rate of MG2 stator burn-out. I welcome the improvements of the ZVW30 and 'Prius c': ZVW30 - mechanical and electrical characteristics similar to Camry and Highlander Prius c - use of ATF cooling as well as improved stator technology and elimination of another step-down gear If these changes show up in the next generation Prius, buyers will have a great buy. Bob Wilson
It was my impression that transaxles do fail in high milage gen 2. I just wrote this in another thread: Luscious Garage | Blog | Gen 2 Prius (2004-2009) Transmission Failure, P0AA6, P0A92, P0A7A writes this: we can describe Gen 2 Prius transmission failure as routine, somewhere between 150-250k miles. The most common indication is trouble code P0AA6 While there are other potential causes of P0AA6, the most common by far is winding deterioration in the traction motor
Source: Luscious Garage | Blog | Gen 2 Prius (2004-2009) Transmission Failure, P0AA6, P0A92, P0A7A NHW20 transaxles do fail but there appears to have been a qualitative step improvement over the earlier NHW11. Key technical changes include use of a bearing replacing a bushing, higher voltages, and a lower viscosity oil. From memory, the Toyota SAE paper claimed a 30% improvement in transaxle efficiency which lowered the heat load. Like many things technical, especially one as radically new as the original, NHW10 transaxle, there has been a steep learning curve and we're still seeing improvements. The original NHW10 transaxle had seals that kept the stators separated from the transmission oil. I suspect there will be more. Low hanging fruit: 'dry' instead of 'wet' differential - today it sits in a pool of oil like 99.9% of all differential gears but there is no technical reason why manufacturing precision and pressurized oil couldn't handle the load and substantially reduce stirring losses. filter - the initial manufacturing debris from our 5,000 mile test and carry forward suggests the oil could be kept cleaner. electrically driven oil pump - provides oil at a constant pressure regardless of engine or vehicle speed. lower viscosity oil - a transmission that runs cooler does not need a heavier oil that thins with higher operating temperatures. Improving the transaxle pays big dividends because it handles the engine power. For an engine running at say 33% thermodynamic efficiency, every 1% percent transaxle improvement has about a 3% (1%/33%) improvement in vehicle fuel efficiency. The Prius c transaxle has made significant improvements in rolling drag and this can be found in the EPA, roll-down coefficients. Bob Wilson
