As a general rule of thumb, the older a car is, the less likely it is to be ULEZ exempt. This is because cars built and registered before 2005 didn’t often consider the Euro Emission standards, meaning that more cars made in that period fell below that threshold.  That said, it doesn’t mean that all old cars aren’t ULEZ exempt, as many are. Also, plenty of modern vehicles also emit too many emissions to be fee-free. That’s why it’s always important to check with a ULEZ checker to make sure that your car is okay.  The ULEZ is based on emissions and not age. So, although age isn’t the main factor, it is likely that new vehicles will produce fewer emissions.  If you own a petrol car, it’s highly likely that it will meet the ULEZ standards if it was registered after 2005. For a diesel car, you can be confident that it’ll be okay if it was registered after 2015.