Spain has reduced the speed limit on major rural roads to 90km/h (56mph), from 100km/h.
The measure took effect on Tuesday, after the authorities changed more than 2,700 road signs at a cost of €526,000 (£457,000; $602,000).
The aim is to get into the safest group of EU countries for rural drivers: below 30 deaths per million people.
In Germany, meanwhile, the government has resisted pressure to introduce a speed limit on motorways (Autobahnen).
The argument in Germany centres mainly on fine-particle exhaust pollution and CO2 emissions, which increase at higher speeds.
But cutting road accident deaths is also part of the debate in Germany.