Was at a family friend's house yesterday and this topic came up. Why does Lexus require premium gas when Toyota doesn't? For example, the 2012 Lexus ES350 comes with a 3.5L V6. The same motor the 2012 Toyota Sienna, 2012 Toyota Camry, etc came with. The Sienna and Camry don't require premium gas. But, the Lexus does. I had no answer for this. Looking for some insight from some fellow forum members.