Here's the big problem with the REx - at least in my case, I realized I'm only going to need it when driving on the highway.
When do I drive more than 80 miles in the city in a day?? Never.
And it's on the highway that the REx reportedly doesn't do very well. I'm referencing the Telegraph UK article:
"I thrummed along at 70mph, but it soon became clear that at this kind of speed our comfortable range between fill-ups was more like 40-50 miles."
It's not an option for me to drive below 70 mph - and I think doing so, at least here in the north-east, or west coast, is dangerous. No one really drives 55 mph! So cruising at 70-80 mph is the norm that the i3 needs to maintain.
At this speed, and then adding cold weather (0F) - which by others' estimates will reduce range by over 50% - you are looking at 20 (winter) - 50 miles of highway range on the REx.
So if you need to drive 70-80 mph on the highway, you're not going to get more than 20-50 miles on the REx tank. You'll need to fill-up - at best - every 30 minutes!
So that's a real bummer…. And compounding this, for US/Canada, the REx only comes on when SOC is 6%. So here's what the Telegraph article said about that:
"...but once the charge runs down to five or six per cent and the range extender cuts in, if you keep driving at 75-80mph it can’t maintain the charge.”
So now you must reduce speed below avg highway cruising speed…
Putting this all together, if you're in the US/Canada, the REx will give you +40-50 highway miles, if you drive < 75mph… and maybe not uphill.
To me, it's just not worth buying the REx in that case, and lugging it around everywhere you go, and reducing the battery's effective useable range by 10-30% (depending on how you look at the efficiency advantages of the BEV).
I just don't know if the BEV alone will work either… in very cold weather I'm worried the range will be something like 20-30 miles.
Hmmm…. I love the i3 but living in cold climates and needing it for highway driving may not be a good fit, REx or no REx.