MGS AutoMoto provides independent, fee-based advisory services to collectors navigating the acquisition, sale, and long-term management of vehicles.
The practice is advisory-first, discreet, and focused on clarity, transparency, and market context.
Unlike other advisory services, MGS AutoMoto fees are structured primarily as flat retainers to minimize conflicts of interest and ensure advice is not influenced by transaction outcomes.
Advisor, not broker.
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Strategic advisory for buyers and sellers, offered on a retainer basis. This includes collection strategy, review of potential acquisitions or dispositions, pricing realism, and guidance on auctions, online platforms, and private markets.
The advisory also supports existing collectors looking to thoughtfully diversify their collections into motorcycles.
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Selective seller-side representation on online or live auction platforms. This may include pricing and reserve strategy, listing preparation, and auction management.
Representation is offered under a separate mandate, structured as a flat fee or commission depending on format and risk profile.
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Ongoing collection advisory and coordination for collectors with multiple vehicles. This includes inventory structuring, historical and market research, valuation context, and coordination with third-party providers.
About the Founder
Mathieu Guyot-Sionnest is an independent automobile advisor with a background spanning auction houses, market strategy, and collectible vehicles across cars and motorcycles. He has worked closely with collectors, institutions, and international clients, advising on pricing, positioning, and transaction strategy within both traditional and online auction environments.
Mathieu managed the live sales of more than 1000 collectible vehicles while working at auction houses, including about 150 from personal consignment and conducted the appraisal of more than 300 vehicles, including Collections of well-known collectors and institutions such as the Petersen Museum in Los Angeles, CA.
Mathieu is also a veteran vintage car racer and experience Concours d’Elegance Judge, experiences that inform a practical, first-hand understanding of vehicles beyond their market value alone. This perspective shapes his approach to advising on quality, originality, and long-term collectability, while having access to virtually any collectors across the globe.
Based between Los Angeles and Paris, Mathieu works with collectors seeking clear, informed guidance on acquisitions, sales, and the long-term coherence of their collections.