I would sooner spend a bit more on a reliable car than risk breakdowns with a cheap one.

would 是情态动词 will 的过去式，在这里表示假设或意愿，带有"宁愿"的含义。 sooner 是形容词 soon 的比较级形式，原意是"更早"，在这里与 would 搭配构成固定短语 would sooner，表示"宁愿"。 would sooner 是一个固定搭配，表示"宁愿...也不..."，用来表达强烈的偏好或选择。