Sparen means both to save money and to economise on anything. German appliances have Sparprogramme, cars have Spritsparen, buildings have Energiesparen. One verb covers thrift and efficiency, and Germans use it for both without noticing the join.
Sparen means both to save money and to economise on anything. German appliances have Sparprogramme, cars have Spritsparen, buildings have Energiesparen. One verb covers thrift and efficiency, and Germans use it for both without noticing the join.