It has more competition this generation, Shift 2 just launched for example.

Especially with its lackluster FW sales!

Sure but it's certainly a possible reason for the recent drop off it has had as mentioned by Carl

But its been dropping off every week for a while now way before Shift 2 was unleashed (get the lame pun :P)

I think GT5's low weeks as of late could be a any one of the following (or a combination of them)

1. It took so long to come out that more people then usual picked it up right away (especially since it was released during the Christmas season) leading to less sales then was expected later on.

2. It may be undertracked especially in EMEAA where sales are harder to track (which is by far GT5's best region)

3. The racing genre isn't quite as popular as it once was.

4. Here's where I agree somewhat with you....GT5 has more competition then it once had...but really the only sim game I would consider competition for GT5 is Forza. All the others like Shift are such small players that they wouldn't impact GT5's sales really at all.

Yeah I think Shift 2 will be the lowest selling NFS game to come out yet...duel releases a year probably isn't helping it either.

Honestly, I think GT5 may be somewhat undertracked.  If it is just due to not much interest in the title, I'm sure that will be remedied once it and the PS3 recieve a price cut.  Though, I do have a hard time believing that if sales have truly been this lackluster for the past few weeks/month, Sony wouldn't have already stepped in with a price cut of some kind.  Maybe even a small one to $49.

I havent even seen any advertisement for shift 2 unleashed and it even got beat by Tiger Woods pga tour 12 lol

Sure but Mario & Sonic already shown casual stuff sells well on Wii ;)

Name me (other than COD) 3 games which has sold over 7 million 3rd Party on the 360, then PS3, seperately

Name me how many core games reached 2 M sales on Wii ;)