Compared to what? Compared to a 3 speed automatic, yes, there is a big advantage, that being that you can have an overdrive ratio for slower engine speed and increased fuel mileage at highway speeds. Also, you can use a lower (Higher, numerically) differential ratio for acceleration, allowing the overdrive to drop RPM's to a reasonable level for cruising. For example, if you lock OD out on your 4 speed automatic so that you're in 3rd gear, you'll observe that the RPM's at 60 MPH are probably 2800 rather than 1900 in OD. Of course, going all the way back to 2 speed automatics like the Powerglide, the advantage is even greater. The fewer gears you have designed in, the more compromises you have to make. For a 2 speed automatic to give decent acceleration, you have to force the engine to buzz at highway speeds (or have a huge engine with lots of torque so it can give acceleration with a high (lower numerically) gear ratio). Suffice it to say that your Intrepid would be much slower with a 3 speed unless it was geared way down, which would increase gas consumption.
Compared to a 5 speed, 6 speed, or even the 7 or 8 speed automatics coming on some cars, the 4 speed is at a disadvantage. The more gears you have, the better you can choose ratios to keep the engine in the power range you want. All things being equal, a transmission with more gears should give better acceleration, and OD can also be a higher ratio for better mileage.
Last edited by CluelessinMO; 09-26-2008 at 02:17 PM.