I never played LFS, so I cannot say anything about it. What I can say is that I love GT4. It might not be perfect physics-wise, but it is thrilling, I enjoy everytime I play it. I am no mechanic or car engineer but I know ho to tune my car some. I like to see a great variety fo cars and courses, real courses. It does not have online playing, but we all hope it will make it for GT5.
Speaking of GT5, it may have all those imporvements LFS has, and many more. And the day is yet to come when a computer game runs better than a console one with only a $200 budget for hardware... while you people spend $1000+ on a brand new computer every Moore's law-cycle (or whenever the newst version of LFS or whatever needs a 4D video card and a Pentium XII 10Ghz with 4Terabyte RAM to play smoothly, we spent at most (including wheel, CDs, etc) $500 for the last two generations of GT.
I want a game to play at my leisure time. Leisure. Entertainment. If I want the most realistic s**t and physics simulator, I just get my car and go for a ride...