Good morning, everyone. Before I hand over to Ken for a financial review of the year, I want to provide a high-level review of the overall performance of the company last year. 2021 was a year of extraordinary progress for Aston Martin. Executing on Project Horizon, we made considerable changes throughout the company and are now operating as an ultra-luxury brand. There have been three key catalysts for the improved performance. First of all, we successfully rebalanced front-end supply to demand early in the year and have become a truly retail-driven business, with retails outpacing wholesales by a significant margin. We delivered over 6,000 core wholesales in line with our plan, and this, combined with historically high pricing, led to a near doubling of revenue. Our adjusted EBITDA improved significantly, delivering a 13% margin, and free cash flow showed a considerable improvement, as Ken will explain shortly.
On the product side, we launched and delivered exciting new additions to our breathtaking product portfolio. DBX accounted for around half of our wholesale volumes in the first year, taking an estimated 20% market share. The DBX product portfolio is expanding with our first derivative launched in Q4, the straight-six mild hybrid, and the DBX 707, which is the world's most powerful luxury SUV, unveiled this month. Of course, we started delivering the era-defining Aston Martin Valkyrie program to customers in December. Although the quantity was less than we initially target for, we refused to compromise on quality, and I'm extremely proud of how we've reached the summit of this engineering challenge despite the difficulties on the supply chain environment. We have heightened both brand awareness and desirability, investing in various initiatives across multiple platforms to expand our reach and product understanding.
Operationally, this has been a strong year of delivery with many initiatives accomplished in an incredibly short amount of time, highlighting our transition to become a more agile business. Plant efficiency initiatives have driven a 20% reduction in manufacturing costs across our sites. With further manufacturing cost savings targeted for this year, which will help offset supply chain pressures. Additionally, we have brought in a number of talented hires to strengthen commercial, technical, and operational teams as we transform into a tech-oriented business whilst fostering engineering excellence within our corporate DNA. I'm also proud to announce today that we are taking significant strides to meet the challenge of becoming a world-leading sustainable business with a commitment to the Science Based Targets initiative net zero standard. First, I will hand over to Ken, who will take you through the financials.
Thank you, Tobias, and good morning, everyone. 2021 was a transformational year for the company as we executed on Horizon and delivered strong growth throughout the business. Although challenged by the ongoing pandemic and supply chain disruptions, we delivered over 6,000 units and significantly improved profitability, in particular on the core business. Starting at the top left, wholesales increased 82% to 6,178 units, following the rebalance GT and sports stock level and a full year of DBX, which contributed over 3,000 units. This also represented a 5% improvement over 2019, with a substantially healthier stock level. Revenue saw a 79% increase over 2020 and a 12% improvement over 2019, driven primarily from the increased wholesales and record pricing from our core portfolio.
Adjusted EBITDA of GBP 138 million benefited from the wholesale and pricing dynamics mentioned earlier, as well as from Horizon benefits. Please note, core profitability is substantially stronger compared to 2019, with less reliance on specials and stronger, more robust retail demand and pricing. We had a free cash outflow of GBP 123 million, which was a GBP 416 million pound improvement year-on-year, largely driven by the improved operating performance of the business. Finally, net debt increased to GBP 892 million, and liquidity remains strong with GBP 419 million of cash on the balance sheet at year-end. Looking at full-year wholesales in a bit more detail. First, on the top left-hand side, we have a breakdown of our models, with DBX representing almost 50% of the mix.
Both GT and Sport improved, and dealer stock levels ended the year at one of the healthiest levels on record. On the bottom left is average selling price. Core, which was a historical high at GBP 150,000 per unit, benefited from a full year of DBX and a significant decline in customer and retail financing. As I mentioned previously, this is a 14% increase compared to 2019 and a 10% increase over 2020. Total ASP was also strong at GBP 162,000 per unit, supported by more specials in the year. Our geographic wholesale split is on the right. As expected, the regional split has shifted towards APAC, up 131%, and the Americas, up 115%, reflecting the impact of DBX.
Within APAC, China, a key geography for us, recorded its best year ever, delivering over 1,000 vehicles for the first time. EMEA and the U.K. also saw positive increases of 47% and 35% respectively. Slide 8 shows the revenue impact of higher volumes and pricing dynamics, which were the largest catalyst of the 79% improvement to GBP 1.1 billion. Moving down the income statement, we have adjusted EBITDA of GBP 138 million with a 13% margin. The most significant benefit to adjusted EBITDA was the flow-through of higher wholesales year-on-year. Net pricing reflected the lower retail and customer financing and stronger pricing dynamics seen across the industry.
Net operating expenses increased by GBP 25 million on the year due to the investment in fixed marketing ahead of our exciting new product launches, as well as through the non-recurrence of furlough credits. Below EBITDA, D&A increased by GBP 57 million to GBP 212 million as we delivered a full year of DBX and started deliveries on the Aston Martin Valkyrie program. This is slightly below our original guidance, reflecting a timing shift associated with Valkyrie deliveries. The adjusted net financing expense increased to GBP 171 million due to the larger balance of notes in issue and a GBP 12 million revaluation headwind from FX movements. Finally, a word on the non-cash adjusting items of GBP 32 million, primarily relating to the GBP 34 million fair value movement on our outstanding warrants attached to our second lien notes.
All this led to a loss before tax of GBP 214 million, over a 50% improvement year-on-year. Moving on to cash flow on slide 10. From the loss before tax and adding back D&A and other non-cash items detailed on the slide resulted in GBP 124 million of cash generated. The working capital inflow of GBP 56 million was comprised of a receivables outflow of GBP 75 million related to supply chain issues, pushing more deliveries into December than originally planned, which is now unwound in 2022. This receivables outflow was broadly offset by a deposit inflow of GBP 71 million, highlighting the strong demand for both the Valkyrie Spider and the Valhalla. There was a payables inflow of GBP 53 million.
CapEx was GBP 185 million, which was lower than originally guided as product development plans matured. Net cash interest paid was GBP 117 million. These movements resulted in a GBP 123 million pound free cash outflow in 2021. Now turning to cash and net debt. Our liquidity position remains strong with GBP 419 million of cash at the end of December 2021. Net debt increased to GBP 892 million, reflecting the cash outflow and FX headwind on our USD-denominated notes. We'll continue to review our liquidity on a regular basis with a view to maintaining our diversified and prudent funding position.
Looking ahead, for 2022, we expect to deliver significant growth with core volumes planned to increase by about 8% and wholesales to step up to more than 6,600 units, driven by the launch of the DBX707 and the V12 Vantage. Both of these cars have improved margins, and together with the Horizon efficiency actions taken in 2021, which will annualize this year, we expect to see circa 50% improvement in adjusted EBITDA from the core business. In addition, we expect to ship 75-90 Aston Martin Valkyrie program vehicles in the year. For the whole business, we expect to see about 350-450 basis points expansion in adjusted EBITDA margin year-on-year.
In terms of the shape of the year, Q1 is expected to be the smallest quarter, given the timing of product launches and as we maintain a quality focus for our Aston Martin Valkyrie program vehicle build. Volumes will build in the second half when DBX707 and the V12 Vantage deliveries will be running at full pace. It's worth noting that supply chains globally do continue to experience disruption and our teams remain focused on mitigating any impact on production. We've also given guidance today on depreciation and amortization, stepping up to between GBP 315 million-GBP 330 million due to the Aston Martin Valkyrie program and accelerated amortization of old technology ahead of the new front-engine vehicles in 2023.
We're guiding to interest expense in the P&L of about GBP 170 million at current exchange rates, our CapEx and R&D of about GBP 300 million, and we've reaffirmed our medium-term targets as shown on the chart. In summary, our financial position and trading performance has substantially improved over the past year and positions us well for further growth in 2022 and beyond. This, coupled with efficient capital investment, supports our expectations of becoming free cash flow positive in 2023 and of maximizing shareholder value through sustainable, profitable growth. Thank you, and I'll now hand you over to Tobias.
Thank you, Ken. As we mentioned today, and can be seen on the slide, we have been incredibly busy this year executing on Project Horizon. In the interest of time, I won't go into details again on all of these points, but as you can see, we have truly touched every single aspect of the business. Moving on to slide 15, this is the vision and the future of Aston Martin. Building on the strong foundations laid last year, we are now ready to take off into the next stage of our journey to become the world's most desirable ultra-luxury British brand. The four pillars seen here on the slide underpin our corporate strategy and the roadmap towards becoming an ultra-luxury business. These are brand, product innovation, sustainability, and team.
These are the core principles on the next phase of our journey to accelerate growth and drive profitability, which I will now describe in a little more detail. Starting first with our iconic brand, which is draped in over a century of history and underpinned by fiercely loyal customers. Having enjoyed global affection, passion, and loyalty for 109 years, Aston Martin is now exciting a new breed of customers with our next generation of product, ultra-luxury customer experience, and return to Grand Prix racing. 50% of our customers are now new to the brand, which is a remarkable achievement. Our customers are at the center of everything we do, and it is important not only to retain, but grow the customer base, appealing to new audiences and new markets.
The addition of the DBX has been instrumental in growing our customer base, and DBX now commands an estimated 20% share of the luxurious SUV market, a market which is growing strongly, particularly in North America and China. We have also maintained our double-digit market share in front-engine sports cars. What's really impressive is that we achieve all of this brand strength while dramatically reducing our variable marketing spend. The demand you see now is true underlying demand. This has led to 75% increase in new dealer inquiries as we focus evermore on exclusivity and luxury proposition. Finally, I must mention the return of Aston Martin to Formula One after 60 years, which has enabled us to reach a global audience of 2.8 billion people. This audience is growing very strongly, particularly in the U.S., which is a key target geography for us as a brand.
That exposure is translating into a 25% increase in visits on our website and configurator on weekends where Aston Martin supplies the official safety and medical car, as well as a direct boost into sales leads to dealers. You are now going to see a short video highlighting 2021 for Aston Martin. We're gonna tell you a story.
It's always been part of our history since the company was conceived in 1913. Racing was in our blood.
Moving on to the second pillar of this new era, let's talk about product innovation. Aston Martin has one of the most comprehensive portfolios in the luxury automotive market, with exciting launches coming which will continue to expand our product portfolio. Our core front-engine sports cars continue to perform strongly, and the V12 Vantage is generating excellent customer demand ahead of deliveries scheduled for Q3. I have driven this vehicle and I can attest it is a fantastic ode to the last of an era, and customers seem to agree. In the SUV segment, we released the first derivative, the mild hybrid in China in Q4, and we are excited to start deliveries this year of the DBX707. The highest performing luxury SUV on the market and the new benchmark for performance luxury.
We are preparing to launch the next generation of Aston Martin sports cars in 2023 and subsequently our first plug-in hybrid vehicle. The performance-oriented electrified plug-in hybrid powertrain will underpin the mid-engine range now in development. As the core business continues to strengthen with improved pricing and profit margin, the special programs will become more strategically aligned to our core portfolio, focusing on personalization as we move into the ultra-luxury segment. Of course, electrification is a key focus for our product development going forward. We already launched our first mild hybrid product last year with the DBX Straight-Six, and in early 2024, we will launch our first plug-in hybrid. This will be followed in 2025 by the first Aston Martin battery electric vehicle. By 2030, we will offer a fully electrified portfolio of our classic sports GT cars and SUVs.
Let's take a look now at a short video about DBX707, which we just launched this month, the world's most powerful luxury SUV and a car which I have been instrumental in developing. As you have seen, DBX707 is a stunning vehicle which sets the benchmark for ultra-luxury performance-oriented SUVs, and it is a very important component of our DBX portfolio for the future. It has been extremely well received by the automotive press, as the quotes on the slide demonstrate. The third pillar underpinning our strategy is sustainability. As a responsible business, Aston Martin cannot ignore the urgent need for further action to reduce greenhouse gas emissions, something which was further highlighted last year by the COP26 climate summit.
While electric vehicles have a key role to play, it is important that we are thinking even bigger with a need to embed sustainability principles and practices within not just our product strategy, but also our business strategy. I'm here therefore incredibly proud that in 2021, Aston Martin committed to the Science Based Targets initiative net zero standard, making a long-term commitment to a net zero future for our business. This is a central tenet of our new ESG strategy in which we are targeting net zero manufacturing facilities and a 30% reduction in supply chain emissions by 2030 and a net zero across our supply chain by 2039. We already use 100% renewable energy in manufacturing and have achieved zero waste for landfill.
We are now going further and targeting zero plastic packaging waste and 15% reduction in water consumption by 2025 and are investigating using more sustainable material such as green aluminum. Diversity and inclusion is a clear focus for our future business as well. We are targeting 25% female leadership across the business by 2026. The final pillar of our new era is all about people, which is one of the aspects of our business which I'm most proud of. The mindset at this business has been completely transformed now into a culture focused on engineering excellence, performance, agility, and speed inspired by Formula One. One of the key achievements this year for me has been to build out best-in-class team of senior managers.
We have also further built out the senior team with key hires in operational and commercial functions, as well as the new regional heads in Americas, EMEA, and the U.K. In total, we have almost 20% of the employees new to the company and over 175 new engineers as we continue to strengthen our workforce. In summary, the last 18 months have seen us rise to the challenge and create a strong foundation to build on. We have turned the business around through our Project Horizon program and created a world-class ultra-luxury brand, which would not be possible without the hard work, dedication, and passion of the whole Aston Martin team. Looking ahead, we are extremely excited about the future. I'd like to thank you for joining us on the journey.