So I am sure some of us who have used GE 1.3.1 before probably remember how it has a name changer, which allows you to change the car name here:
But when you look at the white text box that pops up when you change the view in your garage or look at the car in various other parts of the game, you notice the original shortname is still there:
You might be wondering, why is this? Well the truth is, they're two separate things. Much of the GT5 save data is an SQlite database and when viewing the database itself, we can easily see a lot of things in the save game, including the entry for the Toyota I posted above. That being said, here's an explanation for this.
What the name changer in GE 1.3.1. alters is the name_EN section for the car, which is where the name we see in the first photo is stored.
As for the 2nd photo, the car_code section in the above screenshot is what controls the name displayed in the white text box in-game. What the number for the car_code represents is the entry in the game data (not save data) to where the name is stored, namely in the specdb. In this case, that number is 1768 for this Toyota, and when you look at this ID in the specdb, you can see the car's ShortName matches that of what's in the white text box:
So what this means is if you wanted to change the name in the white text box shown in game, pretty much the most you can do with a save editor is change the car_code to reference another preexisting car name stored in the game data. If you wanted to type in something silly or personal though, you'd have to modify the game data itself to do that, which means if you change the name for the Toyota 86's entry, chances are every other Toyota 86 in the game would also have that name too.
Also, it's worth noting when you change the body for your car in GE, it does not change the aformentioned car_code in the save game. Which also explains why we still see the name of the donor car when looking at the white text box in game. In this case, the donor car here was a SambaBus which had it's parts swapped to that of the Beetle, yet it still shows the SambaBus's name here:
So anyways, if you ever wondered why GE 1.3.1 doesn't change the name in the white text box or why swapping the cars parts doesn't change the name either, well now you know!