What P&L owners actually want from optimisation
Vendors pitch optimisation as a savings percentage. P&L owners don’t buy percentages. They buy defensibility.
The distinction matters because it changes what the software has to do.
A percentage is a claim about a counterfactual: what you spent versus what you would have spent. Counterfactuals don’t survive a finance review. The cost line went down four percent, but fuel also moved, volume mix changed, and two customers churned. Nobody can isolate the software’s contribution, so the finance director discounts it to zero and the renewal conversation gets hard.
What a P&L owner wants is a number they can stand behind in a room where someone will push back. That means the system has to show its work: this is the plan, this is what actually ran, here is every deviation and who made it, here is the cost of each deviation. Not a savings figure — an audit trail that makes the savings figure arguable in your favour.
What this implies
Deviation tracking isn’t a reporting feature you add in v2. For the buyer, it is the product. The optimiser is table stakes; half a dozen vendors have a competent one. The thing that survives procurement is being able to answer “how do you know?”
Most optimisation demos spend twenty minutes on the solver and two on reporting. That’s backwards for the person signing.