Havan, May 14: 'All aboard for Capitolio, via Linea!' cries a jitney cab driver looking to fill his shiny black 1947 Chevrolet Fleetmaster.
Eight passengers pack into the car fitted with an extra row of seats, arms hanging out of open windows. The motor roars to life, and the vehicle chugs off in a cloud of black fumes.
In any other country the Fleetmaster would be on show in a museum or in a vintage car collection. But in communist Cuba, more than 60,000 American cars made in the 1940s and 1950s are still on the roads in full use.
Foreign visitors feel they have stepped into a time warp at the sight of tail-finned convertibles, deluxe Cadillacs and Oldsmobiles, De Soto limousines, powerful sporty Buicks, Mercurys, Plymouths and Chevrolet sedans and trucks.
Since the collapse of the Soviet Union plunged Cuba into deep economic crisis in 1991, the old Americans cars have been pressed into service as jitney cabs to fill the void left by a badly deficient public transport system.
But the vehicles that have survived pot-holed streets and the lack of spare parts due to a four-decade-old US trade embargo on Cuba now face a new threat.
Cuban President Fidel Castro has vowed to run the private taxis out of business for charging exorbitant fares and stealing fuel and car parts from the state.
''No one knows how many of these jalopies are going around with diesel motors. Where did they come from? They charge five or six times more than the new buses,'' the Cuban leader complained in a May Day speech at Havana's Revolution Square.
Castro announced plans in February to buy 8,000 Chinese buses and trucks, a $1 billion investment to modernise the island's transport system.
New air-conditioned Yutong buses have begun arriving and are being used initially for tourist tours and inter-city bus services.
The privately owned American cars have been the backbone of Cuba's public transport system for over a decade. Ford and Chevrolet trucks from the 1950s provide services between Cuban towns, with modified cabins that are packed with passengers who often stand for long distances.
Restrictions on private property introduced after Castro came to power in a 1959 revolution make it hard for Cubans to buy cars.
Pre-revolutionary vehicles can be bought and sold freely. So Cubans have dusted off their grandparents' jalopies in growing numbers and used mechanical wizardry to get them going again.
Changing the engine is often crucial.
Some of the finest models of their day are now powered by Soviet-era diesel engines that spew black fumes along Havana's hot streets.
Cubans bypass long lines for the overdue state-run buses and take an ''almendron'' (big almond), as the oldest of the huge gas-guzzlers are lovingly called for their rounded shape.
Despite the tropical heat, they have no air-conditioning, at most a small fan on the dashboard.
The Fleetmaster's only original parts are its body and the chassis. Under the hood there is an engine from a GAZ-51 Soviet army truck. The gear box and transmission are also Russian.
''You can say what you like about these old cars, but they have resolved our transport problem and allow us to get about town,'' says Carlos Vidal, a hotel employee.
The sturdy American-made ''almendron'' remains a vital means of transport for many Cubans.
''People need us because of the lack of public transport,'' says jitney driver Roberto Carmenate, proud owner of a 1956 Chevrolet Bel Air.
A cottage industry of black-market mechanics has developed to cobble together parts needed to keep the vintage cars on the road, from homemade piston rings to brake pads.
Their ability to improvise is astounding.
Carlos Castellanos owns an impeccable 1952 Buick Special. But raise the hood and you are in for a surprise. The engine is Romanian, the steering is from a Citroen, the gear box is Toyota, the pistons are Mercedes, the fuel pump Mitsubishi and the starter motor borrowed from a KIA.
A private taxi driver in Cuba, driving 200-250 miles (300-400 km) a day, cannot do better than a mid-'50s Chevrolet sedan converted to diesel to cut his fuel costs.
The Chevy is the car that needs least overhauling, says Roberto Diaz. ''A 1955 or 1956 Chevrolet is the most durable car. Some even have the original factory engine working.'' ''I never thought these cars could last so long, a whole lifetime,'' said taxi driver Reinaldo Armengot. ''The makers must have made a mistake.''