Is there any reason you can't just keep an extra few gallons of diesel in your garage? Diesel isn't a particular hazard storage-wise, and can sit for a long time. I don't see how you'd run through a whole tank, and then through that extra few gallons, without being able to refill at some point. It's kind of fun to be able to say "Oh, in an emergency, I can run my car on ______!," but I find it hard to believe any such emergency would arise, unless you don't have a diesel station within 500 miles of you.

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1987 300D, arctic white/palomino--314,000 miles
1978 240D 4-speed, Euro Delivery, light ivory/bamboo--370,000 miles
2005 Jeep Liberty CRD Limited, light khaki/slate--140,000 miles
2018 Chevy Cruze diesel, 6-speed manual, satin steel metallic/kalahari--19,000 miles
1982 Peugeot 505 diesel, 4-speed manual, blue/blue, 130,000 miles
1995 S320, black/parchment--34,000 miles (Dad's car)