Up for sale is a good working, used BMW 318 4 cylinder ignition coil pack assembly. This will work on many 318 & Z3 models. These generally last around 150,000 before a failure, but when it does fail it can prevent the car from starting. If you have no spark this is often times your problem.  Some external corrosion is normal, but if there is a significant amount, this can cause this unit to NOT WORK!   Generally if there is a problem with the ignition system on older BMW's it's either this unit or the wiring to the crank / cam sensor that goes bad. These are fairly easy to replace, and they are over $387 from BMW for an OEM Bosch unit. 

Get the part you need here for cheap! Thanks for looking!