Sparr nodded but hesitated. "One of the vans—sensor's failing. It'll look okay on short runs, but long routes will skew the map. If you want long-term gains, replace that module."

Sparr's fingers hovered over the keyboard. He knew the legal edge. The courier wanted slightly leaner fueling maps, gentler throttle curves, a softened intake map that would reduce fuel consumption on the stop-and-go routes. On paper it was innocuous. On paper is where the company would sign and move on. But dig a little deeper and the options broadened: you could hide extra power in "eco" mode that only showed itself under certain loads, or obscure a particulate correction so emissions readings looked clean at inspection. Tuners called that manipulation; clients called it optimization; regulators called it fraud.

The manager signed the work sheet and handed over cash with a practiced absence of surprise. As he left, Sparr felt satisfied but not triumphant. He'd steered away from the slippery path of outright manipulation that would have buried risks and paved short-term savings. He'd done his job toward a sensible compromise.

Evan sat across the table and read Sparr's notes, nodding slowly. "You ever thought about teaching that? Not the hacks, I mean the honest stuff. People need to know there's a line."

Sparr looked at the laptop screen where the saved tune hummed like a contained storm. In a world where code could bend rules, where every byte carried both promise and peril, he realized he had a small leverage point: to choose, each time, to shepherd machines toward reliability instead of sleight. It wasn't the grand heroism of legislation or mass protest. It was a weekly, deliberate ethics—tiny calibrations that kept vehicles safe, inspectors honest, and drivers a little less at the mercy of cheap fixes.

He pulled up the courier’s fleet profile and ran the simulations. With careful adjustments to injection timing and throttle targets, he could shave three percent from fuel use without touching emissions control curves. Three percent was enough to keep the client happy and the inspectors satisfied. It required patience and a nuanced map, not a sleight of code. He made a note to flag one stubborn van whose oxygen sensor reported irregular readings—old hardware, likely needing replacement. Fix the hardware, he thought, and you'd get a better result than a software hack.

Evan popped his head in through the open door, smelling of pizza and college lectures. "How was the courier job?" he asked.