A nationwide raid on a criminal group recently netted the Spanish police an extensive booty: 52 cars and motorbikes, as well as two boats, and 6.5 tons of gold and silver. Rather than let the spoils go to waste, the Spanish interior minister and other top security officials lighted on a novel cost savings in these hard economic times.

Four of the cars, it turned out, were newly armored and better than the ones they had. So they decided to use them. Jorge Fernández Díaz, the interior minister, got special permission in April from a court in Valencia to use the armored cars for police purposes. The court is handling the investigation into the criminal group and overseeing its seized assets. Confirming a report published this week in the newspaper El Mundo, Mr. Fernández Díaz stressed the cost savings of the unconventional vehicle upgrade.

Four bulletproof cars used by the criminals are valued at about 400,000 euros, or nearly $540,000. “We are saving money for the public treasury, for citizens, and we are raising our means to fight these gangs with greater efficiency,” the minister told reporters. The secretary of state for security and the director general of the Spanish police are also using confiscated armored cars, which are far newer as well as lighter than their previous cars. In any case, officials said, the previous cars had been due for expensive maintenance and repair work. A 2011 cease-fire by ETA, the Basque separatist group, prompted significant cuts in government spending on armored vehicles and bodyguards to protect officials. The cease-fire also coincided with a financial crisis that put the spotlight on unjustified government spending in a time of austerity, which left many Spaniards struggling with tax increases and salary cuts. During a four-decade campaign of terrorism, ETA killed more than 800 people in bombings and assassinations. José María Aznar, a former Spanish prime minister, escaped with light injuries when his armored car was bombed in Madrid in 1995. At the time, he was the leader of the opposition Popular Party. But ETA, which issued a statement this month saying it had dismantled its military wing, has not killed anyone on Spanish soil since 2009. Spain’s government, however, says that the group must surrender unconditionally and turn over all its weapons. Defending the use of the confiscated armored cars, Mr. Fernández Díaz said it was not unusual for crime money to aid Spain’s public finances, or for the Spanish state to make use of “decommissioned” assets after criminal cases are closed.

Last year, for instance, money seized and accounts frozen as part of drug trafficking cases added €22.1 million, or nearly $30 million, to the Spanish treasury. Before getting the armored cars, the minister said, his security forces had already inherited some boats and aircraft from criminals, without providing a detailed listing. “This is not the first time, and hopefully not the last,” he said. What has become of the boats, he did not say.