Your vehicle may be outperforming your investment portfolio. According to market analyst Jim Bianco, used car prices are rising at a pace that eclipses both the stock market and cryptocurrencies like bitcoin.

"If you want to know what the best investment you probably had in 2021, it’s that car sitting in your driveway," Bianco, president of Bianco Research, told CNBC. He points to the Manheim Used Vehicle Value Index, which has surged more than 20% over the past four months—a steeper climb than both the S&P 500 and bitcoin over the same period. Year-to-date, used car prices are up approximately 50%, a highly unusual move for a traditionally depreciating asset.

Bianco attributes the explosive growth to two main factors: buyers being priced out of the new car market due to semiconductor shortages, and a wave of speculation as people buy vehicles anticipating further price increases. "It has all the tell-tale signs of a bubble," he cautioned.

The data underscores the trend. In November, the average used car price hit $27,569, a 27% year-over-year increase, while new cars reached a record average of $46,320, according to Kelley Blue Book.

Bianco warns that this phenomenon reflects a broader, persistent inflation problem that the Federal Reserve is keen to control. "This is exactly what they don’t want to see happen because this is that self-reinforcing idea about inflation," he noted. While he expects inflation to moderate in 2022, he believes the descent will be slower than many anticipate.

As for when the used car price surge might peak, Bianco admits uncertainty: "This could go on for another year. It could go on for two more weeks. The activity that you’re seeing is probably bubblicious."