WASHINGTON — The Trump administration says people would drive more and be exposed to increased risk if their cars get better gas mileage, an argument intended to justify freezing Obama-era toughening of fuel standards. Transportation experts dispute the arguments, contained in a draft of the administration’s proposals prepared this summer, excerpts of which were obtained by the Associated Press. Revisions to the mileage rules for 2021 through 2026 are still being worked on, the administration says. The Trump administration gave notice earlier this year that it would roll back tough new fuel standards put in place in the waning days of the Obama administration.