The IS is in another class than the Camry. The IS250 isn't that fast either, you'll probably have better acceleration in the '07 Camry V6 than with the IS250, the AWD is slowest of the three. If I remember correctly, its acceleration numbers were the same or if not slower than the current Gen5 V6.
I'm considering buying a new IS, I've test driven it (the IS350, not 250) and its quite a monster when you step on the gas.
But Fungke is right, comparing the Camry to the IS is not a fair comparison especially when considering size - the rear seat room in the IS are tiny, I feel as cramped back there as the Solara, if not more so. So at this point, I'm waiting for the '07 ES, to see if it is comming out with the new 3.5L V6 as well. If it is, hopefully it should equal or surpass the power output in the Avalon (it might even equal that of the IS). That way, I can get more room and more power at the same tim - always a plus
Perhaps you may wish to wait for the '07 ES as well? Then you can make a really fair comparison.
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2012 Lexus RX350 Luxury Pkg w/Nav + HUD, ML & PA
2010 Lexus IS250 AWD w/Nav
2007 Lexus ES350 Ultra Luxury w/Nav, ML & PA
2007 Camry XLE V6
2005 Camry XLE V6