Yep, like Nick said, you have a reservoir for Automatic Transmission Fluid for an autostick transmission. VW started putting these in Beetles and Ghias in 1968 and continued until 1972 1974. When they work right, they are a blast to drive. The problem back in the day was that they were WAY different than the manual transmission. They were, to say the least, over-engineered.
They had a 3 speed manual gear box driven by a clutch and flywheel. You had to shift manually, just like on a manual tranny, but the clutch operated automatically.
When you started to shift, the shift lever had a slight pivot before it started moving the shift rod. At the bottom of the lever was a set of contact points . . . so when starting to shift, the contacts would touch and power a solenoid bolted to the firewall in engine compartment. This would then feed vacuum from a reservoir (it's under the opposite fender as the ATF reservoir) to a vacuum pod on the transmission which would disengage the clutch for you.
We aren't done yet. The flywheel with the clutch on it is driven by a torque converter. That way, you can stop with it in gear just like on an automatic transmission. That's what your ATF reservoir is for, to feed the torque converter. Since it isn't an "automatic" transmission, it doesn't have an ATF oil pump built in. So, the last piece of the puzzle is a special engine oil pump. A typical VW engine has a flat plate covering the oil pump. On an autostick, the plate has a drive shaft that goes through the plate to drive another oil pump outside the engine to pump the ATF fluid.
You had three forward speeds, Low, Drive 1 and Drive 2. Around town, you could put it in Drive 1 and forget it. When you got over about 35, shift to Drive 2. If you needed to take off in a hurry or up a steep hill, you would start in low.
When they started giving trouble, they usually just needed a simple adjustment, but most VW mechanics hated them, so they would recommend just going to a manual. That could be a complicated process on the 68-71 models because VW had a special assembly line for autostick chassis . . . they didn't have a tube for the clutch cable in the center tunnel. Every now and then that line would get behind and they would pull a regular chassis (with the tube) for the autostick line. To convert one without a tube, you had to cut open three "flaps" in the tunnel to get the tube installed. In 72, they dropped the special autostick chassis and all of them got the tube. They were a piece of cake to convert.
I've got a 68 "Automatic Stickshift" Beetle. I hope to get it back on the road someday . . . it was a blast to drive! I've heard that as many as 10% of the Beetles made during those years came with autosticks . . . today they are pretty rare. The good news if you have one is that used parts are available at almost any VW swap meet and not that many people are in the market for them -- high supply + low demand usually = cheap.
