I wonder how stable the IS300 is at high highway speeds. I have driven my sister's Audi A4 2.8 Quattro over 100mph and it feels as steady as a rock. Back in 1990 my father had am Audi A8 (then called V8 Quattro) and that too felt rock steady at high speeds. My sister's A4 feels (and dare I say this) almost as steady as my E55. I wonder whether it's the quattro system that makes Audi cars feel so planted.