CO (carbon monoxide), CO2, and H20 (g) are all colorless.

Your car may be regulated as to ratio of gas/air burned in the cylinder. If there was not even air in the cylinder during acceleration, your cylinder would run "rich" and would you find remninces of poor performance symtoms and fuel economy on both gas and diesel engines and most of the time a smokey tailpipe does not necessarily dictate the above.

I think in my uneducated opinion, black smoke exiting from diesels is a result of "unburnt" oil leaking through the piston rings, hence not fully combusting. Perhaps this happens more often than gas engines because diesels burn at such higher compression ratios than gas engines that the rings give out sooner or the fact that the smoke is coming out of diesels with tons of miles on the engine. It is not uncommon to find diesels with 250,000 + miles on the road daily.

As you can see, smoke does not come out of brand new diesels, it is the ones with lots of mileage. Imagine punching the gas of a brand new diesel and getting that smoke due to lack of air? That would be unacceptable for $50,000.

Just my 2 lire.

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'89 420 SEL
'90 300 SEL
'68 Olds 88 Convertible
'84 300 SD (sold it)