What documentation is required for a vehicle to undergo enhanced emissions testing?

For a vehicle to undergo enhanced emissions testing, it is essential to provide proof of vehicle registration and previous emissions test results. This documentation serves multiple purposes: it confirms the vehicle's legitimacy and that it is registered in the jurisdiction where the emissions test will be performed. Furthermore, having the previous emissions test results is crucial as it can show whether the vehicle has been compliant in the past or if there are any ongoing issues that need to be addressed. This insight into the vehicle's history allows testers to better assess its emissions status and identify any potential problems that may affect its compliance with environmental standards.

The other options do not adequately fulfill the requirements for enhanced emissions testing. While proof of vehicle insurance is important for legal driving, it does not directly relate to emissions testing. A vehicle sales receipt may provide information about the purchase date and price but lacks the necessary details about registration or previous emissions tests. A driver's license is required for identification purposes but does not provide any of the vehicle-specific information needed for emissions testing.