Fuel Savers inc.com

There are very few engine configurations that promise
increased fuel economy and power.  There are few
engines that offer this in addition to reliability.
Today, those across the ocean are enjoying the
fruits of diesel technology revolution. 
Diesels have experienced a great history here in the
United States.  In 1980, General Motors modified
their 350ci gas V8 to run on diesel fuel.  [...]

In passenger cars, the diesel engine has never really
caught on.  During the middle to late 70s, diesel
engines in passenger cars did notice a surge in
sales due to the OPEC oil embargo, although that is
the only real significant penetration that diesel
engines have made in the market. 
Although diesel engines are more efficient, there
are eight historical problems that [...]

As you probably already know, diesel engines get
better fuel economy than gas, simply because they
don’t need to burn as much fuel as gasoline engines
to get the same amount of power.  Diesel engines
are built heavier than gas engines, to help sustain
the added stress of the much higher compression
ratios.
Diesel engines don’t have an ignition system either,
so you’ll [...]