A friend bought the Jawbone ERA last year and claims that he can drive with the windows down, and friends think he is at home.
Jawbone works great for people on the other end. However, being that it covers only one of your ears, it can be hard for you to hear others if there are trunks or other very loud noises going by. Jawbone audio adjusts volume for ambient noise, but there are limits. You could earplug your open ear, which helps, but the jawbone seal is not perfect. This would be a problem with any over the ear system or one ear BT. The custom ear silicone for the Jawbone should help, as I wrote above.
For the noisiest environments, the
Apple in-earphones or something like it, are the best for noise isolation, but the noise cancelation on the bare Apple is not as good as NoiseAssasin 3.0 on the ERA, particularly if the iphone is in your pocket, covering up the on board mics.
It just not a perfect world, my friend