Most passenger cars in the European Union still emit the same quantity of carbon dioxide as 12 years ago, the European Union’s auditing agency warned on Wednesday.

The European Court of Auditors said the 27-nation bloc must “shift up gear” to come close to a zero-emissions car fleet, with electric vehicles playing a crucial role.

“The EU’s green revolution can only happen if there are far fewer polluting vehicles, but the challenge is huge”, said Pietro Russo, the ECA member who led the audit. “A true and tangible reduction in cars’ CO2 emissions will not occur as long as the combustion engine prevails, but at the same time, electrifying the EU’s car fleet is a major undertaking.”

According to the auditors’ report, real emissions from conventional cars, which still account for nearly three-quarters of new vehicle registrations, have not dropped.