How wide is the Micra? I'd be wary about having too much sticking out either side - you might remember before you try to get through a narrow gap, but others might not notice.
Is it under or over seat steering? I'd assume an OSS bike might work on any standard rack, but an USS is a bit wider...
If you can reach, then it might be better to carry it on the roof, either lying down on it's side (I know a couple who carry their tandem that way) or upright, if you can get it to fit on the standard roof carriers. That is a problem if you're short though, getting it up and down.