very well put. i agreed with BM
4 months ago, i was in your shoe also (zrated786) i was deciding a BMW, IS300, G35 coupe and i end up in a bimmer, simply bcos it's my dream car ever since i was a kid.
if you are just shopping for a car ----> by all means test drive till you are satisfied.
if you just want a sporty car go with max HP and what ever your wallet will allow you. if you want's to make your choice a little challenging consider reliability (Lexus won this one). not enough add on maintence cost, time you have to spend taking care of it. (for instance bring it to the shop, fuel consumption, etc) to further complicate stuff, add in thoughts on how much you will spend modifiying it. (aftermarket parts avail. and price)
other than Bimmer and IS300 that you have mention, i would recommend that you look into Audi A4 3.0 (the 1.8T is very under power, it's advertise 170HP, but i doubted; a simple chip modification will bring out a whole lot), MB320 Kompressor,
Saab 93 Aero, RX-8, WRX STi and Acuras.
Bad Monkey said:
Z - you're probably not going to get the most objective answer to your question in a BMW forum, anymore than you would on a Lexus forum.
I like Audis, MBs, Acuras, Infinities (can Infinity be plural?), Lexi, etc, but there is something about a BMW for me that defies reasoning or explaination. Perhaps it was brainwashing through reading C&D for years, but when I finally got to the point in my life where I could afford a BMW, I bought one.
If you don't have that passion burning in you, I would recommend test driving until you know which car is right for you. I'm sure you can find plenty of comparo's and writeups on both cars out there. I ran a quick comparo on the Lexus site (BMW doesn't have Lexus for comparison) and was surprised to find out the model you mentioned is rear wheel drive.
Good luck! The great thing about buying a new car, whichever one you get will be the right one for you...unless you get the lexus J/K!