I think your odometer is broken! 
All seriousness aside, I got 25 MPG commuting at 70 MPH+ once but only after an oil change with some special lubricant added ... but 30? You must have been driving downhill with a strong tail wind while drafting a truck!
All seriousness aside, I got 25 MPG commuting at 70 MPH+ once but only after an oil change with some special lubricant added ... but 30? You must have been driving downhill with a strong tail wind while drafting a truck! 
