An entire marketplace exists on the Internet for tuners, devices that help drivers crank up the power on vehicles and then hide the evidence. We visit a local diesel shop to see how it works.

Mazda dealers will reprogram the PCM and ECM software. This service will be completed for free. Recall notification letters are expected to be sent by Dec. 30.

The nefarious workaround — and the crux of the Dieselgate scandal — was for engineers to reprogram the vehicle's Electronic Control Unit (ECU).

Lawmakers want to know more about Volkswagen's massive cheat — how the automaker used software to crank up the power on a vehicle, and then hide the fact.… ...