Top
Bottom
Top

Car Corner
Manumatic vs. SMG

July 1, 2003
By Scott Lewis

Automatics versus manual transmissions. The debate has gone on for years. Can an automatic do as good a job as a manual transmission? In my opinion, the only reason for this debate is because people want automatics. Why else are there so many different types of manual style automatic transmissions. AutoStick, SportShift, Tiptronic. If you are not driving with three pedals and rowing a stick with every gear change, what's the point?

Apparently it is more than just making an automatic, but making an automatic that can deliver as much of the manual experience as possible, while allowing some people to just "put it in drive and go."

I suspect that a lot of these performance automatic transmissions come about for one of two reasons. 1) Some of them are actually better than a traditional manual transmission, and 2) the manufacturers need to sell the car to people that can't or don't want to drive a stick. For example, a Porsche is a sports car. A real sports car has a manual transmission. But the older crowd that can afford a Porsche 911 may not want to manually run through the gears every morning in rush hour traffic. Maybe the spouse wants to drive the car and he/she doesn't know how to drive a stick. Porsche is not about to miss all these sales by not offering an automatic. But they also want to make sure there is as much performance left as possible. After all, if you are buying a sports car you may want to run through the gears now and then.

So there is a clear need for automatic transmissions even is cars that you would expect should never be associated with "put it in drive and go." 

Lately, we are starting to see a new kind of automatic transmission. Ferrari has a manual transmission where the clutch is worked by a computer. Most people can't afford a Ferrari, but BMW is now offering a variation in this theme. BMW calls theirs Sequential Manual Gearbox (SMG). There are only two pedals, and you can set the transmission in drive and let it do all the work for you. This will satisfy the wife that cannot drive a traditional manual transmission. But the BMW is not a traditional automatic. It is a MANUAL transmission, without the clutch pedal. It still has a clutch. A computer works the clutch to match your driving conditions. You can set the transmission to sportier or softer shifting. And yes, you can set it for manual control of gear shifts.

To shift the BMW you bump the gear shift lever or flip little paddles by the steering wheel. But how is this really different from a true automatic?

I have driven Acura's Sequential SportShift. This is a true automatic. It has a torque convert (a fluid based system that has built-in slippage to allow a car to idle while "in gear"). You can move the shift lever to the left and then push it forward to go up a gear, and pull it back to go down a gear.

The problem with this type of transmission is that it provides a false sense of security. Say you are at a traffic light and you want to manually shift. You start off in 1st gear. You move on, shift to second and third. Now you come to a another stop light. Because you are not driving a real manual transmission you forget to back it down to first. What happens? Do you leave from this light in 3rd gear, as you would expect when manually shifting. Nope, you start in first gear and the car will shift itself up to the highest gear you left of with, in this case 3rd gear.

When I drive a manual transmission I am not the downshifting type. I tend to pop it in neutral and let out the clutch as I use the brakes to stop the car. I have yet to see any kind on "manumatic" handle this chore. Automatics, with or without manual controls, all allow you to coast up to a light without any issues of the engine lugging or stalling. A real manual requires you to shift out of gear while you have the car stopped.

BMW's SMG allows a car to idle at a traffic light by disengaging the clutch. But what about the downshift process. If I came off a highway off-ramp and coasted to a red light what will happen? If I am in manual mode, would I then idle fine at the light then try to take off in 5th gear? Or would the computer realize I came to a complete stop and start me off in 1st gear. How much thinking for me is the computer going to do?

And what about popping it into neutral. Why can't they come up with a simple way to simulate that?

Overall I think that a lot of this manumatic stuff is a lot of fluff so people can run through the gears once in a rare while. I know people who have had the automatic based manumatics that allow manual shifting, and they never (or almost never) use them.

However, this new version using a true clutch based manual with a computer doing the actual shifting has the benefit of never missing a shift, never stalling, being perfect with the clutch, faster than human shifting speed, etc. So maybe we have something worthwhile here.

I prefer the three pedal shuffle. I will need to get some wheel time with one of these SMG equipped BMWs. Until then I won't believe that this isn't just a better way of making a car that you can "put in drive and go."

Bottom