SAN FRANCISCO — Ford Motor Co., Honda Motor Co., and Toyota Motor Corp. unveiled their latest hybrid technology at the first national convention of the Sierra Club, “the world’s largest showcase of hybrid cars,” according to the Associated Press. The hybrids run on a combination of gasoline and electricity. At the Sierra Summit, Ford offered consumers their first peek at its latest hybrid SUV vehicle — the 2006 Mercury Mariner Hybrid. The compact, four-wheel-drive SUV can obtain 33 mpg in the city and 29 mpg on highways. Honda unveiled its latest hybrid offering — the 2006 Civic Hybrid — which can obtain 50 mpg on highways and city streets. Toyota did not introduce any new hybrid models, but it announced earlier this year it would soon start selling a hybrid version of its Camry sedan and a seven-passenger Highlander Hybrid. The company, which makes the hybrid Prius sedan, expects hybrid sales to make up about one-quarter of its total sales by early next decade.