[88carrera]

I was interested in a 1978 911 and was wondering was leather standard, or was it an option?

[APKhaos]

It was an option.
Best way to check is with a hot needle on a hidden part of the material - under the seat, for example. Vinyl melts, leather does not. Might be tough to do this before you buy. There should be an option sticker under the hood, passenger side. Someone will chime in with the option numbers for partial and full leather surfaces.

[Jazzbass]

Not 100% sure about 78, but 85 should be similar. In 85, the only std leather was the front of the driver and passenger seats. The rest was vinyl. 930s of that era came with full leather std.

No, if a car has the full leather interior, every conceivable part will be covered with leather - door handles, dashboard, etc. Often times the dashboard leather will delaminate and be replaced with a non leather one. When checking for a leather interior, I alway look at the edges of the interior door handles. If there are stiches, then its leather. If not, then its vinyl.

[racer]

Leather was an option. If your lucky, maybe you can find one with the funky checkerboard seats.. mmm 1970's

[markwemple]

Of course the best would be cloth (still available then) no hot or cold but and it stays planted much better than leather and vinyl. Best of all no Porsche seam failures!