I know that I can say in three ways if I want someone to do something and I think it’s important to emphasise who does it. For example: I want Joe to repair my car.

I have Joe repair my car.
I get Joe to repair my car.
I make Joe repair my car.

I wonder if there’s a difference among them.

Can we do a range from everyday used form to formal one? Or is there no a kind of difference?

And I have one more question. I met the following line in a song: "The town I loved so well". Is it normal to use "so well" without "so much"? I’ve never met this idiom using this way before. What's the difference between them? I feel "so well" more emotional but I don’t know I just suppose it.

Thank you for your help in advance.
There is definitely a difference in emotional tone between the three sentences about Joe. The first is the most neutral. (Joe is a mechanic, I need my car repaired, I have Joe repair my car.) The last implies force or coercion. (Joe doesn't want to repair my car, but since he works for me and I can fire him if he doesn't do what I say, I make him repair my car. Or, Joe is my teenage son. He crashed the car the last time he drove it, so I make him repair it before he is allowed to drive it again.) The middle one, using "get," implies a certain amount of luck, persuasion or manipulation involved in arranging for Joe to repair the car. (Joe is the best mechanic at the garage, so whenever possible, I get Joe to repair my car. Why don't you get Joe to repair your car -- remember, you helped him paint his house. He owes you a favor.)

Others' opinions may vary, but that would be my way of using the three expressions. As for formality, "get" is a bit less formal than the others - but I think the differences I explained above are more important than relative differences in formality in this case.

As for "The town I loved so well," I'm not sure why people sometimes talk about loving someone or something "so well" instead of "so much," but you do hear it said. (There was a song in the Sixties by Jefferson Airplane that said, "You're my best friend, and I love you so well...") I'm not sure whether there is any identifiable distinction between the two. I'll wait and see what others have to say (as well as seeing if others agree with my opinions on Joe and the car).
Khoff's distinctions are both lucid and accurate, for my money.

As for 'love so much', 'love so well'-- it seems to me that many adverbs will do:

I love her so dearly
I love her so completely, unhesitatingly and wholeheartedly
I love her so little
I love her so seldom

Each has its own meaning, but I don't see much difference between 'much' and 'well' beyond the obvious: 'much is a quantity', 'well' is a quality. Two views of the same madness, I suppose. I admit that 'I love her so poorly' and 'I love her so ill' sound a bit dated.
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Thanks, Mr. M!

The explanation of "Joe and the car problem" was really clear. The differences among these forms weren’t explained correctly in school so I’ve used only "have" in every situation so far. But I thought it must have been some differences. Thanks for your explanation, Khoff!

As for "so well" and "so much", it seems there’s no real difference. Thank you!

Oh…, in my first post I naturally wanted to say "so well instead of so much" and not "so well without so much". Emotion: embarrassed

This is not related directly to your question, but I noticed something about your use of "met", I'd like to offer a suggestion.
We don't use "met" in English in contexts such as "I met this line in a song" or "I met this idiom". "meet" and "met" are almost exclusively used for meeting people, not things.
What you need here is "found", "noticed", or, better yet, "came across":

I [found / noticed / came across] the following line in a song:
I've never [seen / noticed / come across] this idiom used this way before.

Emotion: smile

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Thank you CJ! Emotion: smile