Is line level Bluetooth audio possible with iPhone? In my car i have a 3.5mm jack that I want to connect to my iPhone 5. I currently am just running a standard 3.5mm cable from my phone to the port, but that audio volume isn't that great. So I thought a neat way would be to get a Bluetooth module with a 3.5mm input - like this one and use that. 

But I'm not sure if that would connect via a line level output from the phone.

Is is possible to do line level out without needing an expensive lighting to 30 pin cable -> 30 pin to 3.5mm cable into the car port?

OR is it possible to just go lighting cable to this, right into the 3.5mm jack, would it carry audio???

(there was a goo.gl link here but it led to a 404 or I removed it)
You'll want something like the Griffin BlueTrip Aux as it gets powered from a DC car jack (a.k.a cigarette lighter recepticle) and receives bluetooth music and sends it out a stereo analog connector to your car's AUX in / line in headphone jack.

There are many similar products that are cheaper and larger and the audio quality on some is not as good as Griffin's product, but you can shop around since there are several similar product on the market.

The part you list needs a USB cable and getting that out of a lightning port phone would be far more product than a simple BT receiver.