My Opinion; not spell checked.
Peopele grow up knowing more about gassers.

Gassers are cheaper to buy.

I think it takes more special knowlege to run a Diesel. If proceedure is not followed changing a Fuel Filter can leave you with a Dead Battery.

There is less Shops that you can take a Diesel and get reliable work.

Diesl problems can be more costly to fix.
Last Year My Volvo Diesel Fuel Injection Pump deveoped a leak on the Driveshaft end of it. If someone had to take that to a Mechanic that would have been a IP removal, a Rebuilt Fuel Injection Pump installation and timing all at a substatial cost. Just to cure a leakey Seal.

The newer computerized diesel have simlar problems to the computerizeg Gassers as far as sensors and so on go and it takes a well trained Person with equipment to even find the issue.
Diesel Parts tend to cost more and the Labor tends to be more expensive.

Look at the Cost of the Fuel Injectors on the newest Models.

Gassers are more disposable than Diesels are when it comes to some problem too costly to fix.

A lot of People don't like the smell of Diesel Fuel or handling the Diesel Fuel Nozzle at a Station.
Some People have Spouses that are eventually going to Pump Gas into the Diesel Car.

Issues caused by poor Diesl Fuel quality or contamination can stop a Car and create a large expense just to get the Car running especially if the Driver has no mechanical skills.

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84 300D, 82 Volvo 244Gl Diesel