The factory computer for the yr2000 Mondeo Duratech can be reprogrammed for higher octane fuel. I read it in the factory manual at the Ford dealer. The OBDII connector (think that's the right name) is used and a Ford factory tool called a WGS Computer is needed to do it.
I've been thinking about trying to talk a dealer into doing mine, but it is still under warranty so I don't like my chances.
David
Mondeo ST24 Information Site yr 2000 silver Mondeo ST24 V6 MTX
mods: Custom alloy air intake using K&N RC-3250 air filter; Koni Sports shocks; rear 20mm Selbys sway bar; THF; EBC Greenstuff front pads, custom exhaust.