We do it on the Fokker 70 to reduce brake-wear. It has nothing to do with fuel-saving. The F70 has enough power on the remaining engine to do anything, and since the engines are located at the rear of the aircraft it has no impact on stearing capability.
[edit] just one more thing, we only do it during taxi-in. On taxi-out we always use both engines. It saves us the hassle tu return to the gate if a start-up doesn't go like planned.
[ 13 November 2001: Message edited by: JBravo ]