Walker has been offering the Kohler 26efi on its MT series mowers for quite a while now. We have two of them and love them. They crank right up with no fuss (no choke to deal with) and are ready to go right away. I've never done any analysis on the fuel savings, but you can tell that it uses less than you would think if you are used to carb mowers. I had not heard that there's a 23efi, but I would get one in a heartbeat if I was in the market for a new mower. BTW, we also have two 148Z mowers and they are awesome. Most of our guys prefer them to the Exmark Lazers we run. Our 148Zs have the Kaw 21hp, and it's a great combination.