Motorway

Used car marketplace

PrincipalGenerativeAIEngineer

London, United Kingdom FULL TIME
Market Sentiment
HIGH DEMAND

Neural analysis suggests this role is
optimal for Principal candidates.

The Brief

“Principal Generative AI Engineer at Motorway. Skills: Generative AI, AI Architecture, LLM Expertise, Responsible AI. Set overarching architecture for GenAI. Design and build hardest single pieces of work”

What You'll Achieve.

Shape GenAI platform trajectory; Hold sign-off on materially complex AI systems; Veto implementations not meeting bar; Land high-stakes calls with confidence; Contribute meaningfully to AI usage; Contribute meaningfully to overall AI strategy; Contribute meaningfully to AI infrastructure budget; Define how GenAI is built; Define how GenAI is evaluated; Shape unit economics for years; Ensure alignment with regulatory deadlines

Industry & Context.

Used car marketplace
Problems you'll solve

Design and build the hardest single pieces of work; Taking on problems nobody else is well-placed to solve; Leading highest-risk, highest-reward technical bets

What They're Looking For.

Must Have

8+ years building production AI/ML systems, 2 years at the cutting edge of GenAI, Python, modern API-driven architectures, cloud infrastructure (AWS or equivalent), production engineering instincts (CI/CD, observability, SLOs, cost attribution), LLM APIs, prompt engineering, RAG (hybrid retrieval, chunking strategy, semantic caching, re-ranking), agentic architectures (multi-step, multi-agent, tool use, memory), evaluation frameworks, LLMOps, fine-tuning, Deep understanding of LLM capabilities and limitations, Experience setting architectural standards adopted across multiple engineering teams over multiple years, High-stakes build-vs-buy judgment, Strategic grasp of responsible AI and AI governance, practical experience aligning engineering decisions to NIST AI RMF, the EU AI Act or comparable frameworks, Calm, direct communication with executive and board-level audiences, Coaching credibility with senior engineers

Nice to Have

external technical presence (publications, well-known open-source contributions or conference talks), led an organisation through a major AI paradigm shift, working knowledge of the ML Engineering and platform layer (serving infrastructure, AI gateways, cost attribution, multi-model routing), advised commercial leadership on vendor and partnership strategy, worked in a regulated, safety-critical or trust-heavy domain

What You'll Do.

Set overarching architecture for GenAI

Design and build hardest single pieces of work

Hold sign-off on architectural decisions

Advise on build-vs-buy calls for AI infrastructure

latency and throughput optimisation

Define principles for emerging paradigms

Define responsible AI principles

Align with NIST AI RMF

Align with ICO guidance

Own relationships with model providers

Own relationships with infrastructure providers

Coach engineers across the function

Shape hiring and review processes

Set cultural bar for safety

Set cultural bar for evaluation

Set cultural bar for production quality

Identify what Motorway should stop pursuing

Represent Motorway externally

How You'll Work.

Team & Collaboration

Work closely with engineering leadership; Work closely with wider Engineering org; Advise Director of Data and AI; Advise CPO; Advise wider exec; Pair with senior engineers; Coach engineers across the function

Communication Scope

Calm, direct communication with executive and board-level audiences; Compress technical complexity into decisions

Full Job Description

ABOUT MOTORWAY Motorway is the UK’s fastest-growing used car marketplace - our online-only platform connects private car sellers with thousands of verified dealers nationwide, ensuring everyone gets the best deal. Founded in 2017, our award-winning, technology-led approach has redefined the experience of selling a car. Motorway is backed by some of the world’s leading technology investors, having raised £143 million in Series C funding. This is a unique opportunity to join a fast-growing scale-up at a crucial phase of growth and help change an industry for the better. ABOUT THE TEAM GenAI Engineering sits within Motorway's Data and AI function, alongside Machine Learning and the Machine Learning Data Platform. The team owns the GenAI features that shape how buyers and sellers experience the marketplace, spanning agentic workflows in the customer experience and LLM-powered tooling for our dealer network. Over the next two years the function scales from shipping AI features into running a serious GenAI platform. This hire is the technical authority who'll help shape that platform, working closely with engineering leadership across Data and AI and the wider Engineering org. ABOUT THE ROLE This is the most senior individual contributor role on Motorway's GenAI engineering ladder (IC5 / Principal). You'll report to the Director of Data and AI, advising the CPO and the wider exec on AI technical strategy. The remit is the trajectory of GenAI engineering at Motorway over a two-to-three-year horizon: the architecture, the standards and the strategic bets that no single team can absorb on its own. You'll set architectural direction across the GenAI surface area, hold sign-off on materially complex AI systems, and have the credibility to veto implementations that don't meet our agreed technical, safety or quality bar. You'll shape the high-stakes calls on vendor strategy, model selection, build-vs-buy on platform infrastructure, and our responsible-AI posture, providing the t

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