btk,
Our rentals and loaners go to account 52 "Alternate Transportation" on our financial statement. We do not discriminate with regards to who gets a vehicle to use, our Dealer's policy is "If they ask for transportation, provide it, regardless of where or when they purchased their vehicle".
As a result, our expense exceeds $150,000.00 a month, or about 6% of total dealership gross. We split this 80/20 Fixed over Variable op's (and we wonder why it is so difficult to produce a reasonable return on the Dealer's investment in Service Dept!). This philosophy was initiated by MB-USA and we just took it to the next level. Prior to the Altrans account, we took rentals to policy.
If there are any other MB guy's out there, I would be interested in knowing how you qualify your Client's as to who gets a vehicle to drive.