The V6 Engine.
Pros: More compact, less costly to produce, allows for added interior space.
Without the V6 engine, cars would probably still be roughly the size of battleships. The increasing demand for interior space and a more maneuverable vehicle make the V6 a solid choice for manufacturers. They can fit the same power (or fairly close to it) engine in half the space, allowing for the extension of interior legroom and good bit of added front end snipped off the nose. They also take less overhead to produce. This, in theory, should bring added savings to the buyer. That’s not always the case, but there’s nothing wrong with dreaming.
Cons: Slight loss of power, susceptible to vibration, harder to service.
The Inline-6 Engine
Pros: No vibration, less complex, more powerful.
Traditionally, the inline-6 has been a more reliable engine. Whether this is due to dynamic balance or just the simplicity of design is a mystery. What is true is that they are far easier to work on, and not just because of the added space in the engine compartment, though that helps. The firing order of an inline can only go one of two ways, either from front-to-back of the engine or back-to-front. Since the cylinders are all lined up in an even number, vibration is also nullified. They have a reputation of being very sturdy engines as well. Some of the older Dodge inline-6 cylinders would leak up to two quarts of oil per week and still run for hundreds of thousands of miles (as long as you kept filling them up).
Cons: More expensive to manufacture, less interior space, don’t fit into most newer cars.