Hello Rojie! I thought I would add, the 2AZ FE fitted in the Alphard/Vellfire is also fitted in one of the most common cars in America, the Camry. This car runs on the lowest grade American fuel (which is absolutely terrible) just fine. As far as fuel economy goes, it doesn't really make sense for the Alphard to use a premium fuel to get better fuel economy. Cheaper fuel burns easier, and because we aren't using a performance engine or a tuned 2AZ, there's really not a worry about pre-ignition. I do want to run tests still, data is always the answer.