Throne in Spanish car similar to upmarket German one? (5,4)

I believe the answer is:

mercy seat

I'm a little stuck... Click here to teach me more about this clue!

'throne in spanish' is the definition.
'mercy seat' can be an answer for 'throne' (mercy seat is a kind of throne). I'm unsure of the 'in spanish' bit.

'car similar to upmarket german one?' is the wordplay.
'car' becomes 'merc' (short for Mercedes).
'similar' becomes 'y' (similar in meaning).
'to upmarket german one?' becomes 'seat' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'merc'+'y'+'seat'='MERCY-SEAT'

Can you help me to learn more?

I've seen this clue in The Independent.

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