Manual trannies have closer ratios, and with that in mind, it's only been recently that auto manufacturers have engineered five speed auto trannies. Four gears were sufficient for people who didn't know how to drive stick, so they cared less about performance. However, the trend is shifting in that people want the performance, but they are still lazy bums who don't want to hassle with rowing their own gears. Remember, I don't know how old you are, but I can remember when three speed autos were the norm, and if you had a four speed overdrive automatic, that was COOL! Now, any car that is even remotely performance oriented offers a five speed automatic. It used to be only on the likes of MB and BMW. But now, the five speed auto is in the new Accord, Cadillac CTS, most Lexus and Infiniti models, and you will see a trend to shift towards five speed automatics on most cars. Now, if you have, say, a Buick LeSabre, where your main concern is driving Miss Daisy, then a four speed auto will still suffice. Catch my drift?