[Zephyr0s]

There are a varying number of factors when it comes to the purchase price, this is purely based on my personal experience, and I hope it helps you in finding the best deal. I typically aim to land at around 10-15% off the list price (after adding all options, and before any trade in). This has worked for me with both Audi and BMWs, though keep in mind there are certain dealers such as Porsche that are not fond of entertaining discounts.

Some advice:
-Shop around several dealers, and leave your closest dealer till last
-It more or less comes down to your ability to negotiate (start by negotiating after you have spec'ed all the options needed, always use the final price of the vehicle for negotiation, and not based on the value with a trade in or a lease figure as it will simply confuse you more and most importantly don't be afraid to walk)
-look at the dealer's stock level if possible, it's all about supply and demand (i.e. the market for M340i is substantially smaller, so if there is a high amount of stock, the dealer will likely be more aggressive to sell)
-if you are ordering a new vehicle from factory, your discount level will likely be lower than purchasing one available from their inventory
-take advantage of sale events (e.g. EOFY, end of month)
-leverage corporate benefits if available (complimentary servicing, reduced dealer delivery charge, etc.)
-the more options you add = more room for negotiation (but to be honest, the standard M340i is already very well optioned in Australia, and to OP's point the metallic paint + visibility package is probably all you need in my opinion)
-and a bit of patience & luck, you may be talking to a sales rep who has already made their quota, i.e. they will be less inclined to give you a deal, so either go back in several weeks or speaking with another rep might work in your favour

Good luck!