I will discuss compactifications of eleven-dimensional
supergravity on Calabi-Yau threefolds times a circle, with a certain
duality twist along the circle a la Scherk-Schwarz. This leads to
four-dimensional N=2 gauged supergravity with a semi-positive definite
potential for the scalar fields, which will be presented.
It will furthermore be illustrated how to define a truncation
to N=1 supergravity; and the D-terms, Kaehler- and superpotentials
for these models will be determined. Finally, I will point out a
relation to M-theory compactifications on seven-dimensional manifolds
with G2 structure.