Haven't checked into this at all, just wanted input and places to start looking. I tried to start my 1998 Z3 this morning and just fast ticking is all it would do. Last time I started it was Friday and drove it all day. It has sat in my garage and didn't try to start it till today. When the ticking is going all the lights inside the cabin blink with the ticks. Is it just the battery needs to be jumped b/c it has been very cold? Or could it be the starter? If I have to replace the battery (hopefully all it is) is there a specific brand that I should use or stay away from?

Thanks

99% sure that you got a dead battery. You can jump it, but if you let it set in the cold again for any length of time it will die again. Time for a new one.

dead battery.
If it's serviceable you could try refilling it with distilled water. Jump the car, then let it run for a while.
If it's maintenance free you may have to buy a new one.

The $tealer will prob charge you about $75+ for a new bat. If you go aftermarket you can't go wrong with a Sears DieHard battery or Exide/Champion. I would stick with whatever the original factory specs are. One problem you might have with a Wally-World battery is it may not lock in properly to your tray. Also, since it's in a sealed compartment in the trunk, you have to make sure that your battery is "vented".

IMPORTANT: Before you disconnect the battery make sure you write down your radio security code. Otherwise your radio won't work when you connect the new bat.

If you replace the battery and you still get the "clicking" without a start then it's likely your starter solenoid gone bad = new starter.

Good Luck!

Thanks for the help, so aftermarket batterys do work. How do you make sure the battery is vented? If I call auto zone they should be able to get one for me, or have one in stock. Are there certain specs I need to stay within? Are these specs in the manual? Also I have an aftermarket radio, it was put in the car when I bought it, I have no idea what the security code is, but that really doesn't matter, new radio going in for Christmas, yes I peeked at one of my gifts :)

"Vented" batteries have a vent tube hanging off one side that sticks through a hole in the battery compartment to vent fumes outside the vehicle. All batteries have a vent but you need one with a vent tube.