“Save up to 15% on fuel” sounds like marketing. So let’s be specific about where the number comes from, what it depends on, and who actually sees it.
How Software Improves MPG
An economy remap shifts the engine’s torque curve downwards in the rev range. More torque at lower RPM means the car holds higher gears comfortably at lower engine speeds — and low RPM in a tall gear is where diesels sip rather than drink. We also optimise fuelling maps and, on many vehicles, soften aggressive throttle response that encourages wasteful driving.
The Realistic Numbers
- High-mileage diesel commuters: typically 8–15% improvement
- Vans and delivery vehicles: 10–15%, the strongest case of all
- Towing vehicles and campervans: significant gains under load
- Low-mileage petrol city cars: often not worth it — we’ll tell you
Do the arithmetic on a diesel van covering 25,000 miles a year at 38mpg: a 12% improvement saves roughly £400–£500 a year at current prices. The remap pays for itself within months, then keeps paying.
Economy Doesn’t Mean Slow
Counter-intuitively, most economy-tuned cars feel nicer to drive: the extra low-end torque means fewer downshifts, easier hill work and calmer motorway cruising. You lose nothing in day-to-day drivability.
Cover serious miles? Get an honest assessment of what your vehicle would save — read more about Economy Tuning or book your mobile appointment.