It's a wonder they move at all -- the big old Chevrolets and other American jalopies from the 1950s and 60s that ply the potholed streets of Cuba.
Now, ingenious Cubans have rigged them to run on propane and Cuban police are cracking down, out of fear there are "rolling bombs" on the country's roads, the official newspaper Granma reported Tuesday.
The jimmy rig is done because gasoline is so expensive -- nearly $6.50 a gallon, payable in dollars, in a country where the average monthly wage is around 20 dollars.
Propane gas, used for cooking and heating, is subsidized and much cheaper.
In 2011, 57 cars fashioned to run on gas were detected. Last year the number went up to 124. And just through April 16 of this year, it stands at 110 already.
"At this rate the figure could quadruple, with the danger that carries with it," said Roberto Rodriguez Fernandez of the National Traffic Directorate.
"It is essential to keep one of these rolling bombs from exploding," he told the newspaper.
He said most of the fuel-switching was being done in Havana and with the big old American gunboats that are used as privately owned taxis.