Originally Posted By: Nate1979
What I don't understand is why they cost more. Does it cost more to manufacture a diesel engine?
In many cases, yes. Looking at the current crop of diesel pickup engines, they are considerably more robust than their gas counterparts. The castings are considerably beefier, as are internal components. All that extra material costs money. Diesels also typically have a more substantial emissions system. Additionally, all that extra weight usually requires some additional capacity of the chassis.
Going into passenger car (and small truck diesel) world, those massive changes begin to dwindle. Yes, the components are more robust, but not to the extent of pickups. Considering many gasoline engines are now fitted with turbochargers, high pressure fuel pumps, and high pressure injectors, the differences have been shrinking, but emissions systems typically remain more involved on a diesel.
Where the real cost comes in with passenger cars and small pickups is economies of scale. It costs real dollars to obtain emission certification. It costs real dollars to create a supply chain to source a new engine, especially if that engine is not currently produced in the vehicle's manufacturing region. All that for what... 10,000 units a year? It's hard to even justify the added cost and complexity of diesel production in the US at those production numbers. Now factor in all the customer psychological reasons and not many want to play the diesel game.
VW has had the most success, but even in the case of the Jetta, diesel accounts for a single digit percentage of overall sales. Luxury manufacturers like MB, BMW, and Audi can absorb some of the cost because their profit margins are naturally higher, but their efforts haven't gained much traction in the market. In the world most people live in, the only diesel options are VW and Chevrolet (Cruze and Colorado).