Rear center seat shoulder belt
Installed a retracting rear center seat shoulder belt on my 325i 4dr to replace the OEM lap belt. Pretty easy install, minimal drilling, not that much extra hardware and some cutting of the rear seat and you're done! All told it's less $100. I will post a DIY soon with some pics and hardware list.
1995 325i, 225K miles (yes!), 5sp, LSD, M3 cat back, halo projectors, H&R/Bilstein/etc. suspension overhaul, painted sideskirts...