Unfortunately, under Oregon law, driving offenses (including traffic offense convictions, such as speeding tickets) are not expungable. It is important to note that this includes cases that are dismissed pursuant to diversion.
Thus, when you successfully complete diversion, the case will be dismissed, but the arrest will never been expungable. This means no conviction will be entered, however, the arrest and charge always will remain on your record. Your record will show, instead, that the drinking and driving charge was dismissed, or diverted.