We’re still about a year away from the launch of the upcoming McLaren MP4-12C Spider, but that doesn’t mean that information isn’t trickling out on the upcoming topless supercar.

Just last week we brought you spy shots and a few details about the operation of the top. It turns out we were (probably) right on it’s operation, but guessed wrong at its construction.

A new report from Britain’s Car Magazine says the top will be built from aluminum, not carbon fiber as originally thought. As with Ferrari’s 458 Italia Spider, the roof was engineered by Webasto.

Unlike the 458 Italia Spider, however, the topless version of McLaren’s MP4-12C will retain its transparent engine covering, allowing onlookers to drool over its 3.8-liter V-8. To accommodate the top’s mechanicals, McLaren was forced to lower the plenum cover by some 8 millimeters.

The roof can be deployed or lowered in about 17 seconds, at speeds up to five miles per hour.

Unlike the true open-air experience of the Ferrari 458 Spider, Car tells us to expect the McLaren to be more of a Targa than a roadster. It sounds like the car’s C-pillars will be retained for rollover protection, which may a deal-breaker for those wanting true al fresco motoring.

Although it's far too early to say with any certainty, we'd expect the topless version of the MP4-12C to have performance nearly identical to that of it's hard-top stable mate.