If you can offer an incentive to join a Dealer Cyber-savers club on-line. (Like $10.00 offer their next service or something)
You can start doing Service Marketing Direct via e-mail. In the near future, you will also, hopefully, be able to let these customer schedule their own service via the website. Both of these efforts will lower your current Scheduling and Merchandising Costs.
Also, you have a seamless way to develop Customer Loyalty if e-mail with Service Writers are involved. Think of how much CSI will improve if Service Customers talk to their advisors about that funny e-mail joke they sent out last week instead of their "broken car".
The sky is the limit...