make sure P-Cards are kept within the upper echelons of Finance department, and mid-and-higher ranges of Purchasing personnel.
It's the same song-and-dance I've heard a hundred times;
"It streamlines small transactions."
"It lowers cost."
"It empowers the employee!"
There are small problems with all of this;
1: It actually takes less time for an employee, at his desk, to enter a purchase REQUISITION than it takes for them to drive into town, and buy that XYZ. But what about the online P-Card purchase? If one uses their p-card, they're most likely going to pay whatever the market value of that item is. A requisition for the same item may go through a leverage spend account (national account for Grainger, for example), reducing the price to BELOW the market average WHILE ALSO reducing on freight charges, increasing rebates, etc.
2: A p-card is just a form of payment. Sure, the P-card purchases start small and risk-free, but eventually they transform into large and risk-filled. I don't think i'd have a problem if someone went out and bought a battery with their P-Card. I do, however, have a problem with someone buying a piece of specialized safety equipment with their P-Card. What happens if the safety equipment fails? This is why requisitions-POs are so important; your comapny's terms & conditions frequently go out with the PO. When your shop mechanic uses his P-card, he's signing whatever terms that is put in front of him; the only thing he sees is the product, not the risk.
3: We all love an empowered employee. However, there are Delegation of Authority limits for a myriad of reasons. Financial, SOX, best-practice, cost-control, you name it. The moment that shop mechanic etc gets that P-Card, you've given up the DoA on whatever spend he wants.
Just my .02