iPhone 4 and Prius T3 2006

Welcome ehsanvar, I'm in Ireland and I was looking into this topic too.

I have tested iTrip and Cassette Adaptor. I didn't test expensive ''kits'' as I personally think no point for to spend over £100 on the kit unless it make it looks like standard vehicle equipment (which it never will for that price)

iTrip - I found very difficult to manage it and time consuming for each set up, also I worried about the bottom part of the phone being damaged due to extensive usage of this external device.

cassette adapter (through headset jack) - it works and does it's job, I can even hear my family through all car speakers when they call me. Apparently iphone's mic is ok and they also hear me ok.

the cost of this item (cassette adaptor) is £4 on amazon.co.uk

I also use iphone dedicated holder and iphone cigarette charger with an extension to reach the cable to the holder mounted on from windscreen.

Cigarette charger I got as bonus/free together with dedicated iphone holder which cost £8. so the ''set'' costs me about £12.

Sound wise - you can hear a bit of background noise due to cassette heads touching the deck, however for £12 pounds I don't care.

best of luck with your choice.