Fuel prices are expected to go up.
We saw this last spring, and it hurt. High fuel prices (whether you count it as an operating expense or overhead... and if you're looking for someone to help make sense of things like that, I recommend Ruth King over at TurnOnMyFinancialLightbulb.com) can certainly take a chunk out of your profits.
What t'do, what t'do?
#1 Route Appointments:
If your scheduling tool doesn't provide a routing tool, get one that does. And while some jobs (depending on your line of work or department) may rely on scheduled appointments, there is always work - especially any kind of maintenance - that can be routed. It saves on mileage, which means not only are you driving shorter distances, but your techs spend less time behind the windshield and more time being productive. Another job each day? Just from routing? What?
#2 Add a Fuel Surcharge:
All you need to do is set up a separate line item in your QuickBooks called just that, "Fuel Surcharge", for $5.00 or $7.00 or whatever you decide is appropriate. It's easy to manage (some field service software will actually automate the entry when you create the invoices), and a nice way to generate a bit of additional cost-offsetting revenue without actually raising prices across the board. And for the handful of people who complain? Just credit them back the charge... no harm, no foul.
Now, if gas prices return to those lovely lows ("yeah right!", I know, I know), then be prepared to drop that fuel surcharge. An alternative might to start billing specifically for drive time at a separate rate, or adding the fuel surcharge only to accounts that are a set distance away. After all, you're incurring extra cost to get there. Either way, these are all things that you should be able to set up in your field service software, in order to automate the billing process.
Oh, and as an obvious #3:
Keep your trucks in order. Right, I know, it sounds obvious. But letting your trucks' maintenance slip will increase the cost of running them overall, not just in fuel cost. I know contractors who have identified the life-cycle of their trucks and rotate them out as soon as they hit that date or mileage. Granted, that's not always easy, and if cash is tight it is nigh impossible. But considering the cost of maintenance, it makes sense (full caveat: I don't operate or maintain any service vehicles, so in this case I'm just passing on a tip that makes sense to me, from contractors I know and respect).
How else do you control or offset your fuel and vehicle costs?