What is the difference between future perfect and future in the past?

Question

1. It would be nice to buy a new car.

2. It will have been nice to buy a new car.

Please explain the difference between these.

Answer 1

1. It would be nice to buy a new car.

2. It will have been nice to buy a new car.

The difference between 1 and 2 is complicated, for two reasons:

• Sentence 1 can have two different uses.
• Sentence 2 is unlikely; you would say it only in certain circumstances, and it would not be the idiomatic way of saying what it means.

---

1a. Suppose that you are planning to buy a new car tomorrow. This morning you tell me:

"It will be nice to buy a new car," because you like thinking about the new car you will have.

When I go home this evening I tell my wife about the new car you are planning to buy. I say:

Nima told me it would be nice to buy a new car.

Here would be is your will be 'backshifted' into the past tense, because I am reporting what you said earlier.

1b. Suppose instead that you only wish to buy a new car. You tell me:

"It would be nice to buy a new car."

Here your would be uses the past tense form to express unreality now, because you don't expect to buy a new car.

One expression has two different meanings. You need more context to know which meaning is intended.

---

2. The future perfect construction in Sentence 2 indicates that you expect now that you will be able to say the next sentence at some time in the future—probably tomorrow night when you get home with your new car:

"It has been nice to buy a new car."

This sentence expresses the thought that buying the new car was an enjoyable experience, and you still enjoy thinking about it. However, what we usually say to express this is slightly different:

"It has been nice buying a new car." But a simple past is even more likely:
"It was nice buying a new car."

In either case the way to express now your expectation that tomorrow evening you will have enjoyed buying the new car is this:

"It will have been nice buying a new car."

Notice that these are all about the nice experience of buying a new car. If what you want to talk about is the nice feeling of being finished buying a new car—"It's done! I have bought a new car! I have a new car!*, you will say something different tomorrow evening:

"It is nice to have bought a new car", OR
"It is nice having bought a new car."

And today you express your expectation of that feeling like this:

"It will be nice to have bought a new car", OR
"It will be nice having bought a new car."