I didn't really notice any mileage difference after switching to the gear driven case. I still get about 17-18 mpg on road trips where I'm on the smaller highways (65ish mph). It drops a little to about 15-16 if I'm doing more like 75mph. YMMV though....literally.

Allen Dickenson TLCA #6318 http://www.geocities.com/Baja/Trails/8895/
1995 4Runner UnLimited - Fort Knox - SAS'd,Marlin'd, Locked, Warn'd & Dented.
1977 FJ-40 - Stock