Looking for an external mic to use for voice commands in a car.

Im currently using this:

Amazon.com: Mini Microphone for iPhone 3G/iPod/touch/classic: MP3 Players & Accessories

And although its somewhat more sensitive than the Inspire's internal mic, it doesn't seem to be any more directional, which doesn't limit the noise of the car.

Any recommendations? (And, yes, I am willing to spend somewhat more than the two bucks the above mic costs )

Thanks to all.