This was part of a range of roof stereos created by Panasonic at this time. Someone once said to reflect the success of Starwars and all things sci-fi. Very expensive and well built from accounts of those who work on radios.
The range had various parts, which it is very difficult to get full information on (although copies of relevant adverts and the workshop manuals / installation manuals are available on eBay etc.
The model you have was not fitted to a Lotus. The model above in the range (the RM610) was fitted to the special edition 'Essex' Esprit (launched in 1980) and was apparently a very expensive option at the time. The 'Essex' edition Esprit celebrated Lotus's F1 sponsorship deal with 'Essex petroleum' and also was the launch of the new turbo-charged version of the Lotus Esprit (and all of the additional mechanical and cosmetic upgrades added to the car). All Essex Esprit's (of which there were a very small number built) had an RM610 installed with a separate amplifier in the passenger footwell and a four Panasonic speakers fitted. They also had a unique essex metallic blue paintwork, red ruched leather interior, silver and black compomotive alloy wheels and Chrome and red 'Essex' decals and a unique number.
Lotus then started to build Lotus turbo esprit's without the Essex livery and these had the option of having a RM610 roof stereo as well, so a few do have these. But due to the high cost not many were fitted.
The stereo models as far as I know are:
RM710 (super high end - seen on or two in Citroen SM cars) - silver in appearance and with the most 'digital' features. Tape deck, radio, graphic equalizer - separate amplifier. Green digital display for radio frequency and green lights for buttons
RM610E (more brown / black in colour) - Tape deck, radio, separate amplifier and also includes a graphic equalizer panel which is blanked in the RM610 fitted to the Esprit. No digital display for radio - (back lit tuner strip instead) - green backlighting to this and red lights for buttons. Three pre-sets for radio.
RM610 (same as above but without graphic equalizer module)
RM310 (built in amplifier, tape deck and radio but no presets system as with the above two models)
RM210 - I think this exists but not seen much detail on it.
the RM610 fitted to the Esprit did not have the equalizer as far as I can see - it was also shortened to fit the Esprit roof - to the dome light on the end is removed and the frame cut to fit.
Overall the RM310 is a good unit - it can be repaired - I bought my one repaired and operating - it now has a line in so I can play my phone / other things through it. The RM610 I have does not have a working tape deck but also has a line in and works well for that. That is fitted to my Esprit.
Others will no doubt have corrections for some of this...