This is for those of you who have both gas and diesel mowers. On a percentage, how much less fuel does the diesel use compared to the gas annually. Reason I ask this is my buddy just bought a Gravely 260z with the diahatsu diesel. I told him with no more work than he does how can he justify spending an extra 1k or so over a gas powered mower. His response, "diesels cheaper." I tried explaining to him his .15 per gallon savings is going to take a long time to make back the extra $1000 he spent for the diesel but he just said he'd done his homework. Go figure.