Ok, years ago the safest place was behind the driver.. it was in an NRMA study.... reasons being...

*in the middle... any thing coming through the front window has straight access to baby... and baby has no protection from a seat in front of him/her, meaning straight out the window....

* behind passenger/behind driver... apparently when in an accident, a driver instictivly turns AWAY from the danger (why we hear of driver fine/passenger died etc) so behind them places them safer than behind passenger, who has a much higher percetnatage of danger/death....

But this was a few years ago...

With 3 in car seats, soon to be 4, I have to put them where they will fit though!!! But I always put my little ones behind the driver.. I find as a passenger I can get them better there anyway....