I have the OEM shades on my E90 M3 and my windows are tinted 35%. They only take about 10 sec to take out. I keep mine in all the time. My daughter doesn't complain about the sun in her eyes anymore and it doesn't interfere with my driving. I actually think they look better than the pull up ones that came in my X3.
'13 35i M-Sport X3 | JB4 Stage 1 | BMS Intake | H&R Springs | Gloss black grill | CF Wrap and Coded by me | Recaro Child Seats
'15 M3 DCT AW/SO | RKP Diffuser | P3 | M Perf Spoiler | iND Exterior Trim | Recaro Child Seat