OK, so I'm a little late to answer the question but we just bought a 2008 Highlander Hybrid Limited and returned from a trip to Steamboat from Oklahoma which required two trips throught the Eisenhower tunnel. We had no problem passing trucks, cars or anything else that was moving slower than 75. We had two adults, 2 kids and all the ski gear. As a sidebar, we averaged 25.6 mpg between Denver and Silverthorne and 34.3 mpg between Silverthorne and Steamboat. We're loving it!