This is book #7 in the Doris Fein Mystery, and sometimes Spy, series. I'm very much enjoying re-reading them!
When Doris' beloved TR-7 is accidentally crushed by a load of cement dropped on it she buys a custom-made car that can go from 0 to 60 mph in 4 seconds. With such power at her fingertips Doris takes some lessons at a local racetrack, which, brings her into contact with international playboy and contender for the world’s race car driving championship, Roderigo Alcala. Enter George Case and the IGO, the secret intelligence agency, who wants her to succumb to Roderigo’s wooing. Roderigo’s father is a dictator ruler of a small Caribbean Island country called El Concepcion. Since he is ill and they have discovered oil off the coast, El Concepcion, its ruler, and Roderigo have become very important to the United States government. Soon Doris and Roderigo are pitted against ruthless revolutionaries and at the end their survival depends only on Doris’ driving skills.