One clarification first please: does the Prime electric battery re-charge while driving slow/downhill/cruising? Or can it be only charged off an outlet? From your experience, would a 2020 (or newer Gen IV) Prime have more repair and maintenance issues after 200k mi. than a regular Prius? I need help with a high mile, out of CARB warranty, used car purchase.
It works like a regular Prius, it just has a larger battery and ability to plug-in the battery. It's your choice to plug it into an outlet. The breakeven point on mine is around $0.38KwH; if your paying more than that for electricity - you won't save any fuel money. The key to a high mileage car is verifiable maintenance. The car is well broken-in; so odds are it's running great BUT was is it maintained per OEM specifications????? Was the oil, spark plugs, coolant changed in a timely manner. Was all the safety checks done?? Don't trust someone if they state they do all the maintenance themself. What's their background and do they know what they are doing?? That's why you want verifiable maintenance records. Absent the above; take the car to a third party inspection station for a through 'shake-down', usually around $100-$150. If this is a dealership or auto broker, make them give you a FREE extended warranty package, otherwise NO DEAL The price and profit margins on cars these day are crazy - so a bit of insurance for your large investment isn't out-of-line - IMHO...... Just my 2-cents..... Good Luck....
Think of the Prime (or any plug-in hybrid) as having two traction batteries: a large battery that work like an ordinary plug-in EV; and a smaller battery that works like any regular Prius or other hybrid. Then put these two batteries together as just one slightly larger battery with two separate partitions, one for each function above. The partitioning is purely in software, not in the physical battery hardware. In normal conditions, the larger EV portion works the same as any other EV, and is never automatically recharged by the engine. The smaller hybrid partition is managed the same as a traditional Prius, and does automagically recharge from the engine. From a full charge, the EV partition is used first, the engine doesn't turn on until the EV portion is empty and the car switches to hybrid mode. In cruising, the computers do use the engine and short downhills and braking to keep the hybrid partition charged as needed. Then there are special case exceptions. There is a button you can push to force the engine to charge most of the EV partition. Though this defeats the whole fuel-savings purpose of plugging in, so should not be used for regular driving. Use it only for things like adding charge to sneak home silently at night without waking up your partner or neighbors, or not running the engine in underground parking garages, or certain downtown zones (mostly in Europe so far) that don't allow gas engines during peak hours, or emergency electric power for your house during power outages, etc. The car also will charge the EV partition on long mountain downhills that more than fill up the hybrid partition. Where a regular Prius fills its battery and starts spinning for ICE for engine braking, the Prime can continue sending the regenerated energy into the battery for much longer, refilling some of the EV partition too. Though I find on my similar RAV4 Prime that it runs into protection limits for battery charge rate and heating, so begins using engine braking long before the EV partition is filled. A separate button allows you to switch from EV mode to engine-based hybrid mode early, saving some EV battery charge for later.
