The 4CLT emerged from experiments Maserati conducted through the 1947 season, fitting tubular chassis sections to existing 4CL cars to address torsional rigidity problems that had become apparent as engine power increased. The tubular construction — denoted by the T in 4CLT — proved sufficiently successful to form the basis of a revised model. Alongside the chassis changes, the inline-four engine received a twin-supercharger upgrade, lifting power from the 4CL's approximately 220 bhp to around 260 bhp. Other changes included roller bearings for the crankshaft, forged rather than cast rear suspension components, and hydraulic dampers incorporated into the design from the outset.
The 4CLT/48 earned its Sanremo nickname from the race at which it was first entered: the 1948 San Remo Grand Prix. Alberto Ascari won that debut race, and the name attached itself to the model permanently. The Sanremo era continued strongly through 1948: Luigi Villoresi and Reg Parnell won five of the remaining season's races.
In the inaugural Formula One World Championship of 1950, the Sanremo's best championship result came when Louis Chiron finished third at his home race, the Monaco Grand Prix — the highest Championship classification achieved by the 4CLT family.
For 1950 Maserati upgraded the engine substantially: a multi-part crankshaft, lightened and balanced connecting rods, a more powerful supercharger pair, and revised ignition timing raised claimed output to 280 bhp while 10 kg was shed from the car's weight. This brought the Maserati close to Alfa Romeo 158 levels of outright performance, but the decade-old fundamental design could not sustain it — engine failures became a recurring problem and limited Championship Grand Prix wins. That season's Formula One victories were confined to non-Championship events: Juan Manuel Fangio won the Pau Grand Prix, Reg Parnell won the Richmond Trophy at Goodwood, and David Hampshire won the Nottingham Trophy.
Between 1948 and 1950, the 1949 season represented the 4CLT's peak competitiveness. The combination of Ascari, Villoresi, Parnell, Fangio, and Toulo de Graffenried won nine of the first fifteen races of 1949. De Graffenried's victory in the British Grand Prix was the season's most prestigious result. The second half of the season, however, saw increasingly competitive Ferrari and Talbot cars restrict the Maserati to only three further victories as the balance of power shifted.
Minor updates for 1949 — revised brake drum cooling and small cockpit layout changes — produced a specification sometimes called the 4CLT/49, though the factory never used that designation. Late in 1949 a small number of Sanremo cars were converted for Formula Libre races in Buenos Aires in the 1949–1950 Temporada series, with engine capacity enlarged to 1,719 cc; these were designated 4CLT/50 by the factory, though the name is sometimes loosely applied to 1950-specification Championship cars.
Privateer Enrico Platé converted a 4CLT/48 into a Formula Two variant, removing the superchargers, raising the compression ratio sharply, and enlarging capacity to 2.0 litres. Prince B. Bira modified his 1949-specification car to accept a 4,450 cc naturally aspirated OSCA V12 producing around 300 bhp; with it he won at Goodwood in 1951, but the car retired on the first lap of the 1951 Spanish Grand Prix, its sole World Championship appearance.
The last 4CLT variant to appear in the Formula One World Championship was a 4CLT/48 modified by the Arzani-Volpini team, which failed to qualify for the 1955 Italian Grand Prix.
With the switch to Formula Two regulations for the World Championship from 1952, the 4CLT chassis was found to be overweight and underpowered against newer, lighter machines. The car that had been the backbone of top-level European racing from the late 1930s through the first two years of the World Championship rapidly fell from favour. Today many examples survive and are regularly campaigned in historic motorsport, as well as displayed in museums. The Sanremo's role as the most widely raced car at the dawn of Formula One makes it a significant landmark in Grand Prix history.