It's the closest we're ever going to get to a simulator for consoles in this day and age. At least until GT6 comes out or Turn 10 decides to make Forza realistic enough.
There's been at least 1 situation (it's the only 1 I've heard of and I don't really pay attention) where some guy had played GT5 A LOT. So they made him do a lap on the 'Ring in a stock E92 M3. Then they made him do it in real life. And I'm pretty sure he had never driven an E92 M3 in real life before. He set a time similar to his GT5 time and the only reason it was slower was because of traffic. And you'll actually see that, temporarily, he was actually quicker in real life.
Here's the video:
http://www.topgear.com/uk/car-news/gran-turismo-5-vs-real-nurburgring-bmw-m3-2010-12-03
Sorry. but tell me how it's not good enough to be called a sim?
Now yes there are better, more realistic racing sims you can get like iRacing I think it's called for the computer, but I couldn't care much less for PC gaming. Almost everyone I know uses a console anyways. And the few I know that are PC gamers have consoles as well.
And I was never told to like Gran Turismo. I've just always been a PS guy and Gran Turismo was/is it's flagship racing game so I got GT3 way back when. I liked it because it was just a good game. And I've played some NFS and FM games and I actually own TDU2 (just because it has the Ascari A10 and it was cheap) and the previous F1 game. The F1 game was pretty good realistic wise but the rest were terrible, especially TDU2. Don't even get me started on how terrible the driving physics are, how stupid the "racing" is, etc.
Forza is never AS bad as I've sometimes commented on YouTube, but it isn't good either. For example, one of my friends has an Xbox360 and Forza 3. He claims he's good at it. One time he came over and he wanted to play GT5. So we did. I let him get used to the different controls a bit by himself (I had to take a dump) and then we did a 2-player race. We both agreed to choose the same car, with the same settings, and do the same full-throttle starts. I chose an easy track, the High Speed Ring and 5 laps. Stock Ferrari 458s with TC on 5, ABS on 1, Skid Recovery Force on, all other assists off, and in manual. Very easy car to drive right? Put it this way, I'm FAR from the best of drivers, but that race I felt like I was Ayrton Senna and he was somebody who just got their license with the way he drove. He tried changing down to slow down instead of braking the whole time. I stopped counting the number of times he spun and hit the wall at 10. After I lapped him he said this game was stupid, so we quit and just messed around with the game after that. I'm not the best at Forza 3, but I sure didn't spin and crash on nearly every corner.
Then NFS,
for whatever reason, I've always affiliated with the crappy-ness of the Fast and Furious series which I always affiliate with ricers.