Modern diesels start very easily except in exceptionally cold weather. They’re no less “instant” than a gasoline engine in temps above 30F.
If you wanted to make one of these diesels run as smoothly as possible, well, that’s a simple matter of choosing an engine design with a multiple of 3 cylinders, and not in a V-configuration. American auto designers need to get their heads out of their V-8 obsessed posteriors and rediscover why 3 and 6 cylinder inline configurations are naturally smooth, ie, without the need for a balancing weight on the crankshaft. Most “real” diesel engines are inline-6 configurations. Most dieselheads know that most of the V-8 diesels produced were less than desirable engines from a standpoint of reliability and fuel efficiency.
If you want the engines to be particularly smooth on startup, then use compressed air to start them.
A diesel hybrid would probably get over 100 MPG in urban driving because a hybrid drive system would exploit the ability of a diesel to run most efficiently at one speed, rather than at a range of speeds. A diesel engine prefers operation in a narrow range of RPM much more than a gasoline engine; most “medium speed” diesel engines achieve their highest fuel efficiency somewhere between 1600 and 1800 RPM.
So start the diesel, bring it up to optimum speed, charge the batteries with whatever excess power is left over and shut it down when done meeting the temporary power demands.
I don’t see why a 90 degree v8 would be any less smooth than a straight eight. The firing intervals are exactly the same. The firing order may be slightly different, but that’s all.
A straight eight should be smoother than a straight 6.
A v6 is a stupid design. It’s impossible to get an even firing interval from a v6, 90 degree or any other angle.
There is a diesel hybrid in the works but batteries aren’t part of the plan. Instead it uses hydraulics to compress nitrogen and uses that for the initial acceleration from stop to about 20mph. It’s a great design for urban delivery type vehicles, buses etc. Ford is hopefully going to show an F-150 at the Detroit auto show in Jan with a production model for the 2009 model year although I think it may be with a gas powered engine. UPS has been testing the concept in their delivery vans.