My 2012 LS460 has an accelleration issue. When the engine's warm, if you take your foot off the brake after a complete stop, the car lurches forward. Lexus mechanics say it's working properly, as designed. Also said that if they had speed bumps in the dealership lot, the car would go over them without applying gas! Anyone else having similar issues? Awfully dangerous. I've driven lots of different cars & have never experienced this issue.