Only two, that we know about, reached that number. In hundreds of users, only two reached over 170 km, and both stopped at 175 km (seems the odds are in my favor). I believe for these two guys the car offered the possibility of using all the energy from 4,105V to 2,750V lower cell voltage, when the car was in the beginning of its life. For all the other users, when new, the car will stop at 3,6/3,5V lower cell voltage, so no way it will let you get 175 km of mRR. Maybe one of these days appears a new guy in the block, but for now it appears no one has a special i-MiEV like us. Yes, I believe you need a special i-MiEV to reach 175 km, and there are two possibilities: the inicial capacity is stated to get the 175 km number, by someone who have the knowledge and the means to do that, or the car, after some use, calibrates its capacity to an higher number then the inicial one.
The second happened to me.
So, I'm very confortable that this is the maximum number we can get, and it will be very difficult to see more guys going over 170 km.
Riding an i-Miev since 4/2011 in Portugal, 100.000 kms.