Hello, I need new brake pads for my 2011 Z4 and I'm going to replace the rotors as well and was wondering what are the best pads and rotors to purchase and from where?
If you're happy with the stock pads & rotors, I'd say stick with those. Stick with solid rotors, avoid slotted or cross-drilled. Bavauto.com, autohausaz.com are just a couple of many places - you can look up part numbers on realoem.com. Rotors and pads are sold by lots of places, if you google the parts numbers you'll probably have a lot of hits. Price-compare Roundel advertisers too. Brembo & O.E. BMW should be good quality for stock rotors. If you drive in winter weather, I always found semi-metallic pads to lack cold bite when backing down the driveway when in sub-freezing temps - so o.e. or ceramic pads might be better if you're in northern climes.
I purchased vented slotted discs from Turner Motorsport and had ceramic pads installed. Stops on a dime and I get little or no brake fade when I track the car. If you plan to track the car look at brake fluid upgrades as DOT 3 will boil at pretty low temps.
If you think the BMW OEM rotors are good enough, or, your pads are so far gone, they are cutting into the rotors, I'd save the money and just have the rotors machined. Since I've turned 70, and don't enjoy cleaning wheels on Saturday, look for pads that shed little dust. Those pads will last a bit longer. Don't invest in "lifetime" pads, those are so hard as they wear down they cut into the more expensive rotors. As far as expense you can buy rotors at OEM standard, or go very deep, and buy rotor that have been deep frozen in nitrogen for a real cost. Where you really can do yourself a favor is change the pads, machine the rotors, check the calipers and piston, and above all change the brake fluid. The fluid will attract humidity and will move the water to the caliper pistons, and rust the walls and pit them. Use a good quality brake fluid to replace what's in the car.