No, you really don't but it's not up to me to tell you that. (but auto is rubbish).
Auto in the smart is called 'Softouch' and the semi auto is called 'Softip'.
Adding it involves a trip to smart and throwing a wad of money at them but I will show you how to save some cash before going there. If you have a 600cc smart, you may find it will work straight away after being modified as a small minority has the coding already in place.
The Smart Auto Gear Selector
The entire unit attached to the gear stick is called the 'SE Drive' and there are 3 types.
Semi Auto
Full Auto
Full Auto with Engine Start Button
When smart do the automatic conversion, they remove the soft tip SE Drive and install a soft touch SE Drive. A new gear knob is fitted with a button on the side, a new accelerator pedal is fitted and a TAN code is placed into the SAM unit via the OBD socket.
The SE Drive is about £100, the TAN code is about £100, i'll get back to you on the new pedal but labour will be another £100. As you can see, it's mounting up in price.
How Am I Going To Save Money?
Simple, we are going to reuse your old SE Drive.
Here is the PCB of the full auto 'soft tip' SE Drive.
And here is the PCB of the semi auto 'soft touch' SE Drive.
Did you notice the difference? Of course you did, it's circled in red.
That is the only difference, one small plastic 2 pin connector.
This is the connector that the microswitch normally attaches to but any momentary
(push-to-make) switch will do. Just wire the button to either one of the pads on the PCB.
Personally I don't like the idea of being limited to certain gear knobs just because it
has a switch so I would urge you to do the same and have the switch elsewhere.
The position is only limited by the length of wire you have to hand.
Not using the smart auto gearknob means you save even more money not buying one.
If you want to stick with the standard set up you will need a Burgess F1NST8A1 microswitch.
This sits in the top of the gear stick. Thanks to Ward for that information.
You will also require a smart gear knob with the button on the side.
Anything Else To Save Money?
I believe so but I am making 2 assumptions here which I will test in time.
Firstly, you don't have to have the new accelerator pedal.
The new pedal has an extra bit of travel at the end to engage the auto kickdown function,
it's an idea to get it eventually but not necessary straight away.
Secondly, it is unlikely the old pedal can be modified to add the kickdown funtion.
The older 600cc smart didn't have a kickdown accelerator pedal but obviously
they came with auto so I don't think the kickdown pedal is a factor.
What About Saving Money On The TAN Code?
Yes, you could save some cash on this but you will have to ring around.
I have heard quotes from only £20 up to £150. If they give you a really low quote, make
sure you get the persons name so you can blame someone if they over charge.
There are now cracked versions of the TAN code calculator available,
so now many smart specialists will be able to add auto for not much money.
Conclusion
If you try it out, please let me know how you got on.
So far, three people with 600cc smarts have tried it.
One worked straight off, the others didn't so probably need the ECU updating.
SE Drive Wiring Connections