Originally Posted by SnoFire
What about all the other car companies that use more than 4 gears, are they just not doing it right? There is more to this world than a v8 so we can't compare the gears to just that.
Basically what he's saying is if you have a powerful engine, you don't need as many gears. Which is entirely true, a powerful engine with a large power band doesn't need to stay in a specific rpm range to make its power, so it doesn't need extra gear ratios to keep it in that range.
Adding those extra gear ratios increases the amount of time you waste shifting. In a vehicle without a lot of power outside of its narrow power band, this is more than made up for by being able to stay in its power band, but in a vehicle with a wide power band (think Hemi and other V8s), it's less of an issue.
Extra gears helps low powered vehicles that have narrow power bands more than it helps vehicles with big V8s. Things like the little Honda VTEC engines need more gears to stay in that narrow band (to a lesser extent, you'll see this with the V6 as well).
Reality is, with a powerful engine, more gears is more of a marketing thing than anything.