Key takeaways A remap can improve economy on some turbo diesels, but it is never guaranteed. Auto Express reports claims of 7 to 10 per cent on turbo diesels, and warns that economy can also get worse. Any saving disappears if you use the extra power often. Do not tune for fuel savings alone. Measure your own MPG before and after. Some tuners promise more power and lower fuel bills at the same time. It sounds too good to be true, and sometimes it is. Here is when a remap can save fuel and when it will not. Why a remap can save fuel Factory settings are a compromise between power, emissions, smoothness and cost. A good remap can add torque at low revs, so the engine does less work to hold a speed. You can stay in a higher gear for longer and use less throttle to pull away. On diesels, adjusting injection timing and pressure can also help the engine burn fuel more completely when cruising. This is why most economy claims come from turbo diesels, where Auto Express reports figures of ...
Chiptuning and ECU remap guides: how it works, what you can gain, the risks and how to choose a good tuner.