Salsa singer Cheo Feliciano in San Juan, Puerto Rico, in 2009. (Ana Martinez/Reuters)

Cheo Feliciano, a Grammy-winning salsa singer whose career spanned six decades and encompassed romantic boleros and masterful work as a sonero, a vocalist who improvises rhymes and melodies over thunderous rhythms, died April 17 in a car accident in San Juan, Puerto Rico. He was 78.

He was driving his Jaguar when he lost control of it and crashed into a post, CNN en Español reported. The news channel, quoting police, said speed may have been a factor. His wife told reporters that Mr. Feliciano disliked wearing a seat belt.

Mr. Feliciano, a baritone, brought an intimate, conversational style to the bolero, a genre best known for its dramatic, forceful tenors. His suave stage presence enhanced the romantic effect.

Women, said Latin music historian Joe Conzo, “would swoon over him.”

Jim Byers, co-host of “Latin Flavor” on Washington’s WPFW (89.3 FM), said that Mr. Feliciano’s death was “emblematic of the passing of an era that spanned both the swing-influenced mambo era and the R&B-tinged salsa era.”

Mr. Feliciano sang in the late 1950s and early 1960s with the Joe Cuba Sextet, which competed with the bigger and more-established New York mambo orchestras of Tito Puente and Machito.

Setting his sights beyond the Latino community, vibraphonist Cuba featured two singers — Mr. Feliciano, who primarily sang in Spanish, and the late Jimmy Sabater, a timbales player who sang in English. The group later became known for the hybrid boogaloo genre, which mixed Latin music and rhythm-and-blues influences.

Mr. Feliciano’s early 1960s hits with the Joe Cuba Sextet included the guajira “El Raton” — a metaphorical song about a rat and a cat — and “Como Rien,” a bolero about young lovers roughly translated as “How They Laugh.”

He was also in the whistling and chanting chorus on “El Pito (I’ll Never Go Back to Georgia),” an early pop hit for Cuba. The song’s titular catchphrase came from an earlier song by jazz trumpeter Dizzy Gillespie. The Joe Cuba Sextet reprised the song in a Coca-Cola commercial from that era.

Mr. Feliciano left the sextet in the mid-1960s and worked as a featured singer with pianist Eddie Palmieri. Within a few years, Mr. Feliciano’s career went dormant as he struggled with heroin addiction. He checked himself into a treatment center in Puerto Rico that used highly confrontational therapy groups as an approach to recovery and stayed there for nearly three years.

After he left in 1970, Mr. Feliciano resurged to popularity with the album “Cheo.” The record featured two signature songs written for him by Puerto Rican composer Tite Curet Alonso, “Anacaona,” about an Indian princess killed by Spanish conquistadors during their conquest of the future Dominican Republic, and “Mi Triste Problema (My Sad Problem),” a bolero. He eventually recorded more than 40 songs by Alonso, whose writing proved both danceable and lyrically provocative.

He also recorded with Puente and as a member of the Fania All-Stars, the musical dream team of Latin jazz singers and instrumentalists organized by Fania Records in the 1970s. Mr. Feliciano is featured on a 1975 live album, “Fania All-Stars Live At Yankee Stadium,” which was included in the Library of Congress’s registry of culturally significant recordings.

A carpenter’s son, José Luis Feliciano Vega was born in Ponce, Puerto Rico, on July 3, 1935. (Cheo is a nickname for José.)

Mr. Feliciano studied music from a young age. When he was 10, he started a children’s group called El Combo Las Latas — the can combo — because their instruments were made from tin cans.

When he was a teenager, he and his family moved to New York City. He joined the musicians union as a percussionist and networked with performers from the Palladium Ballroom, a venue that had become the mecca for Afro-Caribbean music. Bandleader and timbalist Tito Rodriquez, one of the city’s most popular Latin singers, hired him as a valet. Mr. Feliciano’s friends told Rodriguez that his errand boy could sing.

“Tito knew me as Cheo, but he didn’t know they were talking about me,” he once recalled. “He said, ‘Cheo, you sing?’ And I said, ‘I’m the greatest singer in the world!’ . . . He said, ‘Well, you’re going to have to prove it now.’ ”

Mr. Feliciano went onstage, sang one of Rodriquez’s most popular songs and was called back for two encores. In 1957, Rodriquez recommended the singing valet to fellow bandleader Cuba, who was searching for a new singer.

Survivors include his wife of 56 years, Socorro Prieto de Feliciano, known as Coco, whom he married the same day that he debuted with the Joe Cuba Sextet, and four children, according to the Associated Press.

In 2008, Mr. Feliciano received a Latin Grammy for lifetime achievement. (The Latin Grammy awards are presented in the United States by the Latin Academy of Recording Arts and Sciences to honor American and international artists who record in Spanish or Portuguese.)

Mr. Feliciano once described his appeal and the qualities that made his style so singular.

“I’m a feeling singer,” he said in a 2000 interview with the Web site “I think of a bolero as when you whisper to a woman in the ear, you talk, you bring through the message.

“I believe that bolero should be in between talking and singing it. So whenever I go into words like ‘amor’ [in a breathy voice], talk about it, not just ‘amoooorrrr.’ . . . And people have said that: ‘Cheo does not sing the bolero, Cheo talks the bolero.’ ”