- Without gasoline, we can't get the DeLorean up to 88 miles per hour.
- So what do we do?

9 seconds sound clip from the Back to the Future Part III movie soundboard.

You can hear this line at 00:38:39.951 in the DVD version of the movie.

Quote context

[...]

- All right. We'll get the DeLorean and get ourselves back to the future.

- Oh, listen, Doc, I tore a hole in the gas tank when I was landing, so we're gonna have to patch it up and get some gas.

- You mean we're out of gas?

- Yeah, it's no big deal. We've got Mr. Fusion, right?

- Mr. Fusion powers the time circuits and the Flux Capacitor, but the internal combustion engine runs on ordinary gasoline. It always has.

- There's not gonna be a gas station around here until sometime in the next century.

- Without gasoline, we can't get the DeLorean up to 88 miles per hour.

- So what do we do?

- Twenty-four!

- It's no use, Marty! Even the fastest horse in the world won't run more than 35, 40 miles an hour!

- Bartender said that's the strongest stuff they got.

- Try it, Marty.

- Give it more gas!

[...]