You got your V8’s. You got your V6’s. I owned a car with a V4 once, but that’s the only time I’ve ever seen one. What gives?
The old saab v4…my guess with the transverse mounted engine in FWD, no need. A Subie is the closest with a flat four for low ctr of gravity (like Porsche),they tend to be rougher. A transverse v4 takes up too much room vertically (as much as a v6/8)…IMO straight alignments are easier to balance; sure there are other reasons.
It’s much cheaper to manufacture a straight four.
There’s really no benefit to it other than balancing issues. But counter-rotating balance shafts are just as effective an easy to intergrate into an inline layout.
Take a look at motorcycles. There are V4s from a few different manufacturers. Here are a couple examples:
-Honda Interceptor http://powersports.honda.com/2009/interceptor.aspx
-Yamaha Royal Star Tour Deluxe http://www.starmotorcycles.com/star/products/modelspecs/413/0/specs.aspx
Basically, a four cylinder works in a similar fashion to two twin cylinder engines. While two cylinders are moving up, the other two are moving down. As each pair cycles together, one is pulling in fuel and the other is pushing out exhaust. This makes an I4 inherently smoother than a V4. Having them in a V formation makes it harder to balance the cycles to make the engine smooth, especially if all cylinders are attached to a single crank pin. With most motorcycles, this smoothness isn’t as necessary. Riders like to feel the vibrations of a V-twin or a V4. However, a car owner would not tolerate the engine vibrations enjoyed on most V formation motorcycles.
I’ve got an 83 honda magna (cycle) with the v4. Whitey is right, the V is easier to balance with more cylinders, and Cylinders can overlap. An inline 8 would be very long. There are 4-cyl “boxer” engines (Porsche and Subaru) where the V has been opened all the way to flat, so the cylinders box each other. It has to do with size, efficiency, cost to manufacture and purpose.
There’s plenty of room to put a straight 4 under any hood. That’s not so for a straight 6. Plus, it costs less to build a straight engine tha a v-engine. There are half as many cylinder heads and half as many overhead cams.
And one more reason motorcycle manufacturers go to the trouble of v4s is to minimize engine width, not an issue in cars, as you mentioned.