Blue Model S photographed in California with wider arches, new rear diffuser, black trim, hinting at upcoming facelift.
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A mysterious 2021 Tesla Model S prototype has been spotted testing in the US, which many believe is our first look at an upcoming facelift for the Tesla's flagship electric sedan.

The blue, manufacturer-registered example spotted by Twitter user @klwtts features a new rear diffuser, black tailgate trim (replacing chrome on current cars) and tweaked revised headlight and front fog light signatures, suggesting an assortment of mild exterior updates are in the works for the Model S.

The test car's wheel arches are also markedly wider than standard Model S variants, leading many online to suggest it could be a development prototype for the upcoming Plaid performance flagship, due to arrive in late 2021 with three electric motors delivering 820 all-paw kilowatts and a sub-2.1-second 0-100km/h sprint time.

Should the standard range receive a facelift, it's likely the Plaid halo would also benefit from the updates – consider this prototype a combination of both.

However, the most significant updates due to arrive with the refreshed Model S are expected not to be on the exterior, but rather inside the cabin, where rumours point to a redesigned dashboard dominated by a tablet-style, horizontal touchscreen inspired by the smaller Model 3 and Model Y.

An interior overhaul for Tesla's flagship sedan would be the second major update since its introduction in 2012, following an exterior facelift in 2016, with no next-generation model in sight.

The 2021 Tesla Model S facelift is expected to debut in full in the coming months, ahead of the Plaid's scheduled market launch towards year's end.