I didn't know whose car was is?还是it was?为什么

I didn't know whose car was is?还是it was?为什么
I didn't know whose car was is?还是it was?
为什么

I didn't know whose car was is?还是it was?为什么
it was
因为这是属于从句部分 需要使用正常语序 即陈述句语序
判断方法：whose是疑问词 把回答代入whose的位置时 你会发现句子的意思即顺序是正确的 你以后遇上这类问题可以这样去检查

it was
whose car it was在句子中做know的宾语，为陈述句，不需要倒装

IT WAS ！不需要全倒