My VW has a built-in handsfree cellphone kit. The mic is built into the headliner, and everything is integrated with the dash, steering wheel controls and radio. It's wonderful. I can leave my phone on bluetooth now, and when I get into the car, the car becomes the handset.
Now I hate people who use cellphones in cars - weaving, slowing down, leaning towards the centre of the car like some they all have some weird disfigurement. Until I had this car, I would never make or take a call when driving. I was derided and made fun of on occasion for pulling into a parking lot to take a call. But now I have an interesting option. Because I don't need to fuss with the phone, I can make a call using the steering wheel controls. Better yet, if someone phones me, I have the option to ignore the call and send it to voicemail.
I'm not sure this is any safer than actually using the phone physically - I find myself distracted a bit when using the handsfree - more so than just talking to someone in the car with me. But it's nice to have the option.
It seems I might be softening in my stance on useless crap in modern cars. This is the first piece of gadgetry I've found a use for.