Evidence is mounting that Ford intends to do something special with the GT. The company is allegedly testing the supercar with a different powertrain on the streets of Detroit, according to Ford Authority. We might have even seen it before.

The unnamed folks talking to Ford Authority say the new engine sounds completely different from the GT's current twin-turbo 3.5-litre V6. There are no further details about what this powertrain is, though.

Gallery: Ford GT send-off edition spy photos

Spy shots (above) might have caught this vehicle on the road. It wears a modified rear deck with a large scoop directing air into the engine bay. There is a rumour about Ford pushing the output of the 3.5-litre twin-turbo V6 to at least 700 bhp (522 kilowatts) and maybe even over 760 bhp (567 kW).

Although, simply turning up the boost on the current engine doesn't seem to fit with the allegation that this engine sounds significantly different than the current unit. In a perfect world, we'd like to think this rumour means that Ford might put a V8 into the GT, but there's no official sign of that right now.

This updated GT also allegedly gains fender vents similar to the ones on the GT Mk II track car. It wouldn't gain the Mk II's massive wing, though.

Other changes aren't yet clear. Tweaks to the suspension and brakes seem likely to cope with the extra power, though.

Ford GT production is supposed to end in 2022. The speculation so far is that this updated model would arrive as a grand send-off just before assembly finishes. However, Ford Authority speculates that the Blue Oval might extend the vehicle's life by building this hotter variant.