If you think Mario kart can outsell GTA4 then you have to be crazy.

Let's look at DMC4 numbers. The combined numbers for both the 360 and PS3 version are slightly over 2 million, and they're still selling. That means that their combined numbers are over every Devil May Cry game except the best selling one. We can infer from that that the combined sales of GTA4 on both platforms will sell at least 14 million (Vice City sales).

I'd seriously like to see Mario Kart Wii reach 14 million or higher. Also consider that San Andreas is still charting 4 years later.

i think gtaiv will easilly outsold mariokart

GTA IV will sell the most for the first few years. BUt with the unprecedented huge expansion of the Wii console base. MKWii will have the best game sales leg after Wii Play, Wii Sports and Wii Fit. MKWii will sell more in its lifetime compared GTAIV combined.

well if mario kart ds just broke 10 million i dont think mario kart wii will be able to do it

hate to point something out but the vast sales of the recent gta games were due in part to the the vast userbase of the ps2, even combined the ps3 and x360 will be lucky to sell much more than half that amount so although gta4 will sell massively i seriously doubt it'll sell more than 10 million (combined) when all is said and done) where as i can see mario kart easily selling that

We are talking about LTD sales here. SMG will have long legs and I expect lifetime figures to end up around 8 million, possibly more. SMG is very single player orientated while Mario Kart is more of a party game. MK will appeal more to the Wii's casual userbase. Indeed, I believe Nintendo themselves describes it as a 'bridge' title, that will draw both casual and traditional gamers alike. A more fitting comparison are games such as M&S @ the Olympics, Mario Party 8 and Carnival games which are all selling well beyond expectations. 

GTA4 will outsell MKWii 3 to 1 hands down. Both will receive awesome sales but GTA is a very popular franchise and will do absolutely great.

Mario Kart Wii vs. GTA4 360 OR GTA4 PS3: Mario Kart Wii
Mario Kart Wii vs. GTA4 360 AND GTA4 PS3: GTA4
So pretty much what everyone else says.

Why do you think that?

OT: I think Mario Kart will outsell each version separately, considering the higher userbase and the appeal it has on casuals and hardcore.

On the otehr hand, MKWii may not be able to outsell GTA4 combined on 360/PS3. If it does, it might be because:

1. The userbase of the Wii will be much higher than both PS3 and 360 combined

or

2. A lot of casuals who bought the game for PS2 may have bought a Wii instead of a PS3 or 360 this gen, therefore not buying the game.

GTA4

mkwii will sell 10 million

gta iv sells 15 lifetime easily.