Screenshot by Nick Statt/CNET

Uber may occasionally fit the Silicon Valley stereotypes of unnecessary excess, what with its helicopter rides on the 4th of July and boat service during the BART strike. But how can you knock the company when it gives its customers a chance to step back in time, through glorious gull-wing doors, into a simpler era of Chuck Berry covers and puffy vest-and-flannel combos?

So for the truly diehard "Back to the Future" fans already dusting off their limited edition pair of Nike Air MAGs, Uber is offering free DeLorean rides to San Francisco users thanks to a partnership with General Electric. The promotion will run from September 6 to 8.

Uber

It's all part of a GE campaign called Brilliant Machines that aims to foster the development of greener and more efficient hardware and software, for powering everything from car motors to city blocks.

How does "Back to the Future" fit in here? Well, the classic film series is at the heart of GE's advertising campaign for the project, "so the turbines today will power us all into the future," says Michael J. Fox in a voice-over for the Brilliant Machines promotional video that features a flying DeLorean in all its '80s glory.

But don't discount Uber's involvement here. The company's "on-demand everything" mission has of late spread to ice cream trucks and flower delivery, and now apparently includes advertising campaigns as well.

Because DeLoreans don't grow on trees -- in fact, the vehicle is quite hard to come by nowadays and used models are still pricy for an '80s relic -- Uber has outlined its strict guidelines for nabbing your DeLorean ride:

- Open the Uber app anytime from noon to 9 p.m. on Friday or noon to 6 p.m. on Saturday and Sunday

- Supply will be very limited, but if your timing is right, you'll see the DeLorean option

- Maximum of 15 minutes per trip and one person per vehicle

Unfortunately, last time we checked, 88 mph was still a tad over speed limit. Oh, and time travel doesn't exist ... yet.