This is approximate:
HP = 218
0-60 manual 6.5-7.0 seconds
0-60 auto 7.5 seconds
Top speed - 143mph
MPG: 20-24
IS versus WRX is asked a lot..
I'll give you my .02 cents since I just went through the same comparison and ended up with an IS.
First of all, there is no comparison. The cars are absolutely and completely different from the ground up. So I'll say in advance it really depends on what you want.
I drove an '07 and '04 WRK, and while impressed with the performance, it was not quite what I expected. The car suffers from turbo lag so don't expect to feel it kick in until about 35mph. The seats were ok, just ok, not that comfy. Interior again wasn't dissapointing but neither was it "wow". The hood scoop is a little over the top and my wife hated it for that reason. In my opinion the car feels heavy. I contribute that to the AWD weight more than anything. It is great for handling, but again, in my opinion, its not an easy car to drive as a commuter. Oh, and it has a terrible blind spot.
On to the IS. First one we drove, we knew this was the car for us. While the performance wasn't quite what the WRX offered, the enterior was miles ahead in comfort, road feel was excellent, and the auto tranny shifted like a dream. The HID lights are incredible. This car is small, so beware. The back seats are great for kids, but adults will be cramped. My only real gripe is the factory CD player went out right after I bought it. This is very common and seems to be the only common flaw in these cars.
Conclusion:
Both cars are tried and true sport sedans from reputable manufacturers. Lexus has the upper hand in steering response, comfort, options, and longevity. Subaru has AWD, turbo, and lots of street apeal. Don't get me wrong, subies are great. My 96 Outback has 167k miles, but I believe that boosting the WRX will significantly decrease engine life especially if it is driven like it is meant to be. On the other hand, the is300 engine is overbuilt to the point of insanity (my opinion) making it a great candidate for moderate modifications while maintaining the integrity of the engine. If you want balls to the wall, die hard, boosted performance, street racer looks, and AWD, go for the Suby. If you want a refined automobile that will impress just about anyone and last for many years, go for the Lexus.
Final thoughts:
Get snow tires for the is300.
*yes, there are many performance parts available for the IS, however, I think you will hit a wall after doing intake, exhaust, and possibly the exhaust cam gear unless you want to fork over $$$ to boost.
Check out www.my.is, there are some fine products there.
Hope this helps.