I have 2 VX's a 2000 Proton and a 2001 Dragon. The Proton runs stock rubber in the summer months and 31/10.50X15 with Rock Crawler wheels in the winter. The Dragon has Nitto 285/60X18 Terra Grabbers. With corrections for the difference in tire sizes, the Proton is getting 14 with the winter blend of gas. In the summer with the stock tires on I was getting 18. The Dragon is getting 14.5 adjusted milage. I haven't had it long enough to give a summer reading yet. The only modification to the Proton is a K&N drop in filter. The Dragon has a Green drop in.