Reprogramming, CO2 & Tax deductibility

Engine reprogramming inevitably involves modifying engine parameters that lead to changes in power, torque and sometimes even maximum speed, which can all influence the characteristics of your vehicle.

When a vehicle is designed, it undergoes a series of tests for certification. “Like in the case of WOT?” you may be wondering. Yes, indeed, but the tests for manufacturers go even further, because the different versions of their vehicles must be validated (e.g. estates, coupés and convertibles) due to varying aerodynamic characteristics which can lead to different emissions test results.

Factors that affect emissions

Many factors can have an impact on the emissions produced by a vehicle. You’ve probably already heard of a “cold start” on a petrol engine, which consists of having a higher engine speed and load at start-up than during normal idling. This heats up the exhaust catalyst, which requires a minimum temperature to effectively catalyse and process pollutants. Other non-temperature-related factors (e.g. rim size and the technical characteristics of tyres) can also influence emissions by modifying resistance, particularly with regard to CO2, the greenhouse gas on which the authorities base their taxation.

Impact on CO2 emissions

In recent years, there has been a race to reduce CO2 emissions, with manufacturers seeking to minimise them by adding mild hybridisation modules (MHEV) or even adopting rechargeable hybridisation with large batteries (PHEV). The aim is to combine power, torque and range at the expense of extra weight, while keeping total emissions below the critical threshold of 49 grams of CO2 per kilometre. The slightest modification, such as changing the size of the wheels or adding options such as a sunroof or trailer hitch, can have an impact on CO2 emissions.

WOT Approach: minimal impact on CO2

This raises the question as to whether WOT-approved engine reprogramming has any impact on CO2 emissions. Rest assured, in the vast majority of cases, the answer is no. Going even further, in all cases of WOT1, our certified reprogramming will have no impact on CO2. In fact, to pass our various tests, we have to comply with the manufacturer’s tests. Our approach is to leave the parameters unchanged at low load, permitting the vehicle to pass the various certification tests as defined in the standards. Of course, unfortunately, this approach is not suitable for all engines. A small engine requires more load than a larger engine to operate, which means it may not be possible to increase power over a wide range of use, making certified reprogramming virtually useless. This is one of the reasons why there are no light-duty vehicles in our catalogue.

Implications for company vehicles

When it comes to WOT3, however, things are different. The addition of certain parts can have an impact on emissions tests and may increase the vehicle’s CO2 emissions. If you own a company vehicle for which tax deductibility is a key factor, don’t hesitate to get in touch with one of our advisers to make sure that reprogramming won’t push you over a CO2 threshold, leading to a bad surprise in terms of tax deductibility or benefits in kind (depending on the country)!