When an easter egg turns out to be a Christmas present

Tesla owners have a new easter egg to play with after the electric car maker added an "Emissions Testing Mode" to its vehicles via an over-the-air update.

At present there are seven fart options to choose from, all named after a product from one of Musk's companies or a recent Musk-related controversy: Not a Fart, Short Shorts Ripper, Falcon Heavy, Ludicrous Fart, Neurastink, Boring Fart, and I'm So Random, which is a random mix of all of the above.

Owners can enable in-cabin toots to be issued whenever the indicator is used or when the scroll wheel on the left spoke is pressed.

Above: Toot toot configuration screen via Microfrost on Twitter.

The easter egg seems to be available for all Model S, Model X and Model 3 vehicles. Sadly this new feature plays a sound via the audio system, but doesn't add a fruity musk, with a hint of aged oak and fresh durian, to the cabin.

After news of Tesla's latest piece of flatulence hit the internet, Elon Musk agreed on Twitter to add a user requested feature: "fart on demand", which would permit owners to use Tesla's mobile app to prank the person currently driving their car.

It's unclear when this new feature will turn up to scare and bemuse drivers.