If the process of making an engine is automated, making a diesel engine shouldn't be that costlier than making a petrol engine. So, why do we make petrol engine?

Let's look at the differences in petrol and diesel engines to really understand the cost difference. 1. Weight: diesel engines are heavier. More weight = more metal = more expensive 2. Turbocharger: All CRDi and the older TDI ones have turbochargers. Cost of a cheap one is 12k approx. (That's for tata indigo) 3. Pump: diesel pumps have much higher pressure output. They need to be better, faster and more powerful. Not to mention durable. 4. Compression ignition: As opposed to electronic. No spark plugs, ignition coil or distributors. Downside, diesel cars have higher compression ratios, more engineering, bigger/ more powerful starter. So just because they're both automated, doesn't make them the same cost. Besides, diesel cars need higher capacity engines, which almost everywhere mean higher taxes.