Hire car and driver Luxembourg to Mannebach, Germany

Why not use the train?

From Luxembourg City, or somewhere else in the country?

My guess is from Lux City to Mannebach a taxi would run around 100 euro

EDIT-- My assumption is that OP is going to the Mannebach that is ~35km east of Luxembourg City

I don't have an answer, but my default would have been CFL, the Luxembourg national transportation authority (note that all public transportation in the whole country is free to use) or the DB, the German national train which also knows about buses, but I have come up blank. Mannebach has no train station and I can't find a bus stop either. There is a bus to Kümmern Brunnenstraße, Mannebach (Saar) but there is also a Mannebach (Eifel) relatively nearby. Which Mannebach are you going to?

The one I looked at (Saar) is a really round about route including 2 buses.

If that is where you are going, I'd agree that a taxi or driver despite the cost is best.

Not much help, eh?

(nice countryside btw)

Assuming the OP means Mannebach / Saar, they could take the train from Luxembourg to Saarburg (with a transfer in Trier; fastest connections 1:07) and then continue by bus to Mannebach (4 connections between 11:30 and 16:00, travel time approx. 30 min). Bus connections can be found on the website of the Trier transport authority: https://www.vrt-info.de/fahrplanauskunft/XSLT_TRIP_REQUEST2?language=en&itdLPxx_contractor=vrt. However, in view of the short distance (10km) taking a taxi won't break the bank (pre-ordering required: https://www.dasoertliche.de/Themen/Taxi-Service/Saarburg.html).

Mannebach / Eifel would be a bit trickier: Train Luxemburg - Cochen / Bus to Ulmen, and then a so called "Rufbus" (60 min. advance booking!) to M. Details at www.bahn.de.