Motorway, the online car dealership controlled by billionaire entrepreneur Alex Chesterman, saw losses triple in 2022 to £43.6 million, which outstripped growth in revenues for the year even though these doubled.
Staff recruitment, increased marketing spending and building brand awareness generally were all blamed for a surge in costs.
An accounting error in the previous year related to share-based payments also knocked £1.3 million off the bottom line.
Sales more than doubled as the value of transactions on the platform jumped to £1.7 billion.
Motorway, which has raised more than £200 million in four fundraising rounds and was valued at more than £1 billion in 2021 said it had "significant cash reserves".
Tom Lathes, chief executive and co-founder, told Car Dealer: ‘Motorway achieved impressive growth in 2022, and we are very proud of these results.
"This accelerated growth is despite a very challenging macroeconomic environment in 2022, with the energy crisis, rising inflation and cost of living challenges throughout the UK."