Smart Forfour 1.5

Vehicle: Smart Forfour 1.5, manufactured in 10/2005.

CAN Baudrate: 500 kbit/s.
Identifier: 11Bit

I've also figured out a little bit by just pressing the buttons to see what changes.

ID: 412h
Byte: 2 bits: 1 - 8 -> Speed.
Byte: 3 - 5, Bit: 1 - 24 -> Odometer reading.

ID: 408h
Byte: 3 Bit: 1-8 -> Outdoor temperature.

ID: 423h
Byte: 1 Bit: 2 -> Ignition.
Byte: 1 Bit: 4 -> Fog lights.
Byte: 1 Bit: 5 -> Fog light.
Byte: 2 Bit: 1 -> Turn signal, right.
Byte: 2 Bit: 2 -> Left turn signal.
Byte: 2 Bit: 3 -> High beam.
Byte: 3 Bit: 1 -> Front passenger door.
Byte: 3 Bit: 2 -> Driver's door.
Byte: 3 Bit: 4 -> Door, rear right.
Byte: 3 Bit: 5 -> Rear left door.
Byte: 3 Bit: 7 -> Trunk lid.

ID: 238h

(No translation needed, as it's already in English.)
Byte: 3 Bit: 2 -> Steering wheel paddle: "Upshift"
Byte: 3 Bit: 3 -> Steering wheel paddle for "downshift".
Byte: 4 Bit: 1 -> "Up" button on the steering wheel.
Byte: 4 Bit: 2 -> "Down" button on the steering wheel.
Byte: 4 Bit: 3 -> Steering wheel button: "Previous page"
Byte: 4 Bit: 4 -> "Back" button on the steering wheel.
Byte: 4 Bit: 5 -> Steering wheel "-" button.
Byte: 4 Bit: 6 -> "+" button on the steering wheel.
Byte: 4 Bit: 7 -> Steering wheel button "Answer call"
Byte: 4 Bit: 8 -> Steering wheel button: "End call"

ID: 443h

(No translation needed, as it's already in English.)
Byte: 1
Bit: 1
Air conditioner

ID: 308h

(No translation needed, as it's already in English.)
Byte: 3 - 4, Bit: 1 - 16 -> Motor speed.

I hope these are the right signals. Have you found any more?