Not exactly, but they are difficult to remember, the IS300 and 400 are the same car just a different engine. And also it's the Toyota Altezza, I don't know any of the other Lexus models really I do find that they are random numbers and letters until you know what those letters and numbers stand for you don't know any the wiser. Peugeot numbers are silly too, just say a Peugeot number to someone and it takes them more than 10 seconds to think of the right one and thats before clarifying that it IS the one you have mentioned.