I spoke to a trucker about this and took some picture of the stuff needed
to clean the carcinogenic particulates from the exhaust.
The World Health Organization has deemed diesel exhaust hazardous to
your health.
Millions of old diesel powered cars are upping the cancer rate in Europe.

The estimated cost of retrofitting a truck is $15,000.
The cost of the Diesel Exhaust Fluid is $15 a gallon.
Many Cal companies are selling their current trucks out of state.
Many small truckers are going out of business in California.
You must have one of these Air Resources Board stickers on your
truck wind shield before you can enter California.

This has increased the cost of shipping in California.

A large turbo compound rotary Wankel would make a great truck engine
due to it's robust
and cannon proof design. There is no doubt in my mind it would last as
long as
a diesel engine and get equal or better MPG. Fuel price per gallon
would be less.
It would weigh less than a diesel as well increasing the payload.
It would also be smoother. Large size is no problem. Some of these
huge Ingersoll Rand
engines are rumored to have run for 20,000 hours.

I am probably way ahead of my time on this one as well.

Paul Lamar

Hi!: below please find one of the many references
available in Entrez PubMed, MedLIne, about the carcinogenic
effects of Diesel exhaust smoke, the nature and
composition of the exhaust gases in a Diesel, and the amount of
particulates, those that give the black smoke look to
the exhaust of Diesel engines may vary, but as long as the
injection pump system is not adequately tuned, smoke in
the exhaust, performances and fuel economy will worsen.

            Best regards, salut +

 Jose Gros-Aymerich
 Madrid, Spain

http://www.ncbi.nlm.nih.gov/pubmed/22393209

"RESULTS:

We observed statistically significant increasing trends in lung cancer risk with increasing cumulative REC and average REC intensity. Cumulative REC, lagged 15 years, yielded a statistically significant positive gradient in lung cancer risk overall (P (trend) = .001); among heavily exposed workers (ie, above the median of the top quartile [REC ≥ 1005 μg/m(3)-y]), risk was approximately three times greater (OR = 3.20, 95% CI = 1.33 to 7.69) than that among workers in the lowest quartile of exposure. Among never smokers, odd ratios were 1.0, 1.47 (95% CI = 0.29 to 7.50), and 7.30 (95% CI = 1.46 to 36.57) for workers with 15-year lagged cumulative REC tertiles of less than 8, 8 to less than 304, and 304 μg/m(3)-y or more, respectively. We also observed an interaction between smoking and 15-year lagged cumulative REC (P (interaction) = .086) such that the effect of each of these exposures was attenuated in the presence of high levels of the other.
CONCLUSION:

Our findings provide further evidence that diesel exhaust exposure may cause lung cancer in humans and may represent a potential public health burden."