Is this a temp gauge?
 

Saw this on a euro SL on ebay. Is that an outside temp gauge under the speedo?

http://i6.ebayimg.com/04/i/000/ff/41/2c25_3.JPG

From here:

http://cgi.ebay.com/ebaymotors/1985-Mercedes-Benz-280SL-Convertible-MINT-77k-Euro-spec_W0QQitemZ320276687718QQihZ011QQcategoryZ6329QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Gauge
 

That's where the Outside Temp Gauge(Digital) is on the newer cars.
I hate to say ,but I don't know on the older Euro SLs.

More Importantly , What's the Black and Orange striped "No No" Zone on ALL
the Kilometers Per Hour Speedometers Between 50 and 60 KPH?


EDIT:
STRIFE wins the prize! Voltage Meter (Or it's a dosimeter for radiation)

Shift points?

^^He meant the the cross-hatched area between 50-60km.

That gauge looks like one of those gauges you would see on the front a of a cobra CB radio, sorry I don't know what the gauge is called.

so thats what goes in that spot. . I figured that styrofoam there wasnt doing anything besides taking up space.... .now I need one, and I'll take that eco gauge while im at it. . .:D

no o2 sensor gauge. .odd. . I always thought '80- 107's had them. . .

I'll bet it's a voltmeter, very professionally installed by someone in that optional area of the instrument cluster (which in 86+ was occupied by the "convenience" lights).

That econo gauge will not work in your car, your is mechanical and that is electrical, i think.

the eco gauge is operated by intake vacuum. The problem lies with the oil pressure gauge, they switched from it being mechanical in the '70's to being electric in the '80's (based on every one Ive seen). Now, If I could find a hybrid, that has an eco gauge and a mechanical oil pressure gauge, id be set.