I am struggling a bit with why a tense has been chosen (which may be more to do with my poor grasp of English grammar than anything else).

One sentence is given as: "Wieviel würde das kosten?" (How much would that cost?), which I think I understand. However, the response to that question is "Das wären 46 Euro am Tag." which is a different tense. Can someone please explain this to me?

The tutors are usually very slow to reply and I like it when people ask questions as it makes me question my own understanding. I had accepted the phrases you mention without really thinking about it.
Actually it seems to be quite complicated and I am not sure that I have fully understood it.

German expresses “would” with the Konjunktiv 2 Präteritum or imperfect subjunctive. The trouble is that for regular verbs this is the same as the Präteritum or imperfect tense so in order to avoid ambiguity German combines the Konjunktiv 2 of werden (to become) with the infinitive of the verb in question, hence in the first phrase we have "Wieviel würde das kosten?" - How much would that cost.

However the Konjunktiv 2 Präteritum of sein is different from the Präteritum of sein so it does not need to be combined with werden so we have:
"Das wären 46 Euro am Tag." - That would be 46 Euros a day. The plural form wären is used because it refers to 46 Euros.

You can Google Konjunctiv 2, here is one example of a link:
https://www.germanveryeasy.com/konjunktiv-ii

I also found Reverso’s conjugator useful for looking up the various verb forms.
http://conjugator.reverso.net/conjugation-german.html

I hope I got it right, perhaps a tutor will comment.

Thanks very much for the description and the links. I'm not sure I quite get it yet, but hopefully if I spend some time going through those pages I'll get there soon!

Richard

Yes it is pretty confusing and complicated and I restricted my explanation to just the phrases you asked about. You see Konjunktiv 2 a lot with the modal verbs such as - ich möchte  - I would like etc.
Here is another explanation of the Konjuktiv 2
http://www.dartmouth.edu/~deutsch/Grammatik/Subjunctive/KonjunktivII.html

If you examine the question and answer in English, you will find your answer.  One is questioning an unknown, whereas one is answering with a known. "How much would I spend"?"  " You are going to spend".  It's the same in German.

@RobertR34
I am not sure that your replay answers the OP's original question. Both "Wieviel würde das kosten?" and "Das wären 46 Euro am Tag." are about uncertain futures.
How much would it cost (if I rented the car)
It would be 46 Euros a day ( if you rented the car)

The question is about the money.  In any case, in everyday German, the present tense is much more likely to be used.  This is a theoretical example with little practical application.

That may be the case, but the OP did ask specifically about the grammar used in the phrases from module 10.3.
Module 10.4 "at the garage" has more on asking how much something costs.

I think one of the weaknesses on the Rocket course is that it sometimes uses grammar that is quite difficult for a beginner to understand without explaining it.
I have often had to resort to other resources to puzzle out phrases. This is compounded by the fact the tutors are very slow to respond to questions if they respond at all.

If you want a solid understanding of German grammar you can use Babbel.  I subscribe to Babbel and they push the grammar sometimes excessively (I think). It makes learning German, for me, difficult because they seem obsessed with rules.  You will however learn why a word such as "wie" is used when our English speaking minds would want to use "was".  They also use ONLY German speakers, and they respond exceptionally quick to questions.

Hope this helps.

Thanks for the advice. I'll take a look at Babbel to see if it helps me.

Just going through the forums and I'd wondered about the initial question on this thread myself while redoing all the early units. Still unclear about how I would choose which one to use or whether it would make that much difference in a practical conversation provided that I got the singular or plural bit right. Bit like the difference between sollen and sollten in the present tense. Certainly no worries about being identified as a foreigner anyway, that becomes obvious immediately after the well practiced stock phrases have been exhausted.

Sorry, that I can't add any clarity but for what it's worth I find very confusing as well.  Perhaps as Fred suggested it doesn't really make much practical difference.  I suspect we are all a bit geeky on issues like this.  Were your mothers school teachers too?

Seems like I am far from the only one struggling. Since I moved to Austria last week, I really hope it becomes clearer soon!

Richard, very little German is spoken in Austria!  Most of them are polite, though, and will answer you in "hoch Deutsch!"

How is that different?  I mean I know Austrians and Germans have different dialects and expressions, but isn't hoch Deutsch the official German language?