That's for 1 gram of Cf-252. Cf-251 is about 400 times more stable according to that Wikipedia page. It's still out of the question that anyone is driving round

That's for 1 gram of Cf-252. Cf-251 is about 400 times more stable according to that Wikipedia page. It's still out of the question that anyone is driving round with 18 grams of any isotope of it, much less 1.4 kg. The documented world production is less than 0.5g per year.