It is difficult to predict if or how ULEZ regulations will change in the future, but it is safe to say that the rules will only become stricter rather than more relaxed. At present the emissions standards required for petrol cars within the ULEZ is Euro 4, which came into effect for most cars in 2006. ULEZ compliance is based on NOx emissions rather than vehicle age, so a vehicle will not become non-compliant because of its age.

However, the Euro 7 emissions standard comes into effect in July 2025, so it is reasonable to expect that at some point in the future the ULEZ standard for both petrol and diesel cars will be raised above the current levels, but it is difficult to anticipate when this might be.