Scooter B123,welcome to LMF. Have you looked at any models?I know eXmark makes the Turf Tracer S-Series,Lazer Z X-Series and Lazer S-Series units.The Lazer Z Xseries uses a Kawasaki FX801v-twin Propane engine ,the L.Z S-Series uses the same engine in it's two models.The turf Tracer X-Series uses an F FX691V Kawasaki V-Twin Electric start Propane,the Turf Tracer S-Series uses an FX600V Kawasaki V-Twin elec start Propane and the Turf Tracer S-Series uses an FX600V-Twin Kawasaki electric start Propane. for 11 acres the first 3 series offers decks of 60",60"and 72" in that order.I paid 1.79 gal last dec for my home tank.I could'nt tell you w/o doing some more research how many gal. any of these models holds nor the acerage you could cut .Nor can I give you any kind of a price on any of the models mentioned but I suspect they aren't cheap.eXmark does have a web site that you could look at.also There are others that offer LP like Dixie Chopper that offer 2 models w/Generac LP engines that hold 2/71/2 tanks and have 60"&72" decks that cut 9acres an hour.again don't know the range on 15gal.russ