* Emissions Regulations: The US has historically had stricter emission standards than some other parts of the world, particularly regarding nitrogen oxides (NOx). Meeting these standards with small diesel engines, which can be particularly challenging to control NOx emissions in, is expensive. The cost of the emissions control systems often outweighs the cost advantages of using a smaller, more fuel-efficient diesel.
* Fuel Economy Differences: While diesels offer better fuel economy than gasoline engines in many situations, the difference is less pronounced in smaller, lighter vehicles. The benefits of a diesel's fuel efficiency may not be significant enough to offset the higher purchase price and potential maintenance costs in the US market. In larger, heavier vehicles, the fuel economy advantage is more substantial.
* Consumer Demand: American consumers have historically shown a stronger preference for gasoline-powered vehicles, partly driven by the widespread availability of gasoline and a perception (not always accurate) that diesels are noisy, less refined, and require more specialized maintenance. This lack of consumer demand makes importing small diesel cars less economically viable for manufacturers.
* Refining and Distribution: The infrastructure for ultra-low sulfur diesel fuel, crucial for modern diesel engines to meet emissions standards, was slower to develop in the US compared to Europe. This made it more challenging to market and service diesel vehicles. While this has improved, it remains a factor.
* Cost of Compliance: The costs associated with certifying vehicles for sale in the US market, including emissions testing and crash safety standards, can be substantial, making it less attractive for manufacturers to import small volume, niche vehicles like small diesels.
In summary, it's not a single reason but a combination of regulatory hurdles, consumer preferences, and economic factors that has limited the availability of small turbo-diesel cars in the US. While the situation is slowly changing, the hurdles remain significant for manufacturers.
