I car share/rotate who drives with my brother-in-law and his Dad, we were also unfortunately targeted on Upper Helena Street last night (2018 Audi). We feared it'd be the case as we passed the BMW X1/X3/X5 with both windows smashed and several other 'more expensive' cars along the road, despite ourselves and a few others we spoke to saying none of us had anything of value on display.
It seemed like mindless vandalism/jealousy and less like 'lets target City fans' as (and no offence by this) we saw several less expensive vehicles with MCFC accessories that hadn't been vandalised, for instance, a small Toyota Yaris in front of us had a miniature MCFC scarf and stickers in the windows yet had not been targeted.
It's a shame, really - we've parked there for over two years now with little issues aside from the occasionally busy garage on the corner taking up the majority of the street with cars due for repair.
As others have said, maybe it's time to find a new parking spot - the cynic in me wonders if the local car parks have paid someone - I wish I had more faith in my fellow Mancunians.