In mileage situations I have taken to printing out a Google maps route or satnav for backup. Really, dranz, your people must have too much time on their hands. One could imagine them querying your mileage next time if it WASN'T 36 miles.

To be fair, I don't think these cost analysers realise how irritating their queries are to business travellers who've been thinking about cost/benefit ratio for most of their career. I try not to take it personally.