Intangible assets, net - Schedule of Intangible Assets (Detail) ¥ in Thousands, $ in Thousands	Mar. 31, 2023 CNY (¥)	Mar. 31, 2023 USD ($)	Mar. 31, 2022 CNY (¥)
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	¥ 35,733		¥ 35,684
Less: Accumulated amortization	(14,139)		(10,140)
Intangible assets	21,594	$ 3,144	25,544
Trademark [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	486		437
License [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	3,530		3,530
Dealership [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	¥ 31,717		¥ 31,717

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
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-URI https://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 340
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Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.

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