I have an original article from 1982 Car and Driver magazing on a 300CDT which states that the turbo not only improves the car's performance, it also improves its fuel economy.......sounds implausable doesn't it.

The explanation they gave is that a turbo diesel engine's combustion process is actually improved over normally aspirated engine because the delay between initial fuel injection and the onset of compustion is reduced as the compressed-air temperature is higher (due to the turbo's compression). This allows more effecient injection timing and improves overall efficiency by about 5%. They also stated that the turbo diesel had better "detonation" behavior than the non-turbo diesel.

The article noted that EPA milage city rating went from 24 to 27 when the turbo was introduced to the 300CD, and highway milage rating went from 28 to 33.

I'm not an engineer but thought this an interesting addition to this particular discussion topic.

Nic
'85 300CD @ 148k miles