Well, just wanted to get everyone's attention, because I am worried about our economy, energy, and our ozone layer. In fact I feel guilty using any kind of mower, but rationalize that at least I mow an acre in no time flat. I use a 54 and a 52, and even tho I am in the mountains, I hope to move to a 62 54 combo. I have heard that a 21 inch (that takes 5 to 6 times longer to do an acre) puts out the same amount of emissions as a large mower per hour! Thoughts?