Westbrook, who will share his Corvette DP with DTM champion Mike Rockenfeller and Canadian Michael Valiante on January 25-26 for the new championship's inaugural event, went around the 3.56-mile road course in 1min39.748s.
"We had a fantastic, trouble-free test and a nice car," Westbrook said of the three-day test.
"Daytona is a fantastic place to drive when you have a nice car."
Oliver Gavin kept Corvette Racing on top of the timing sheets of the GTLM category, his teammate Jan Magnussen having claimed the best time on Saturday. Nobody managed beat Gavin's benchmark of 1min45.915s, set aboard his C7.R.
Mercedes Formula 1 test driver Sam Bird (Starworks Motorsport) led the LMPC field with a 1min42.704s.
Meanwhile in GTD, the fastest lap belonged to Flying Lizard's Markus Winkelhock, who turned a 1min48.862s aboard his Audi R8 LMS.