Mileage seems way off. I was getting up to 27 mpg with my 2005 LS 430. I have 35,000 miles on it and before servicing, I noticed the 'required maintenance' light came on. I placed 93 octane, with 10% ethanol, in it and the mpg went down to 24 (highway). I had the routine 5000 mile service performed, so have to wait until this ethanol/gas is used up before deciding that it was a factor.