...Proven 460 combos, and the build section on this site. From what I have read here, the "magic" 30+ MPG 460 combo isn't likely to happen (even 20 mpg is asking a lot). Past posts have me thinking that the mpg "adverage" seems to run around the 9 to 13 miles per gallon range, bigger mpg numbers seem to be hard to do without fuel injection. A light weight, all 'glass roadster would probably squirt down the road just fine with a basic mileage/towing 460 combo with D-3 heads. Don't know if this helps but you get a bump.