Germany - Early TXL departure: taxi or car service?

My departure from Berlin TXL will be at 6.40 a.m. on Brussels Airlines, connecting on to the U.S. on UA. I know one doesn't need to make very early check-in times at such early hours, when nothing at the airport may be open; I think I should aim to be there at 5.

I see there are public transport options at that hour, but I think in this case I should use a taxi or car service; I guess leaving my vacation rental apartment in Mitte near the New Synagogue at 4.30? Are there any recommendations for a taxi or car service that can be arranged the day before? Can I phone in English, or can it be done online reliably?

Streetcar/U-Bahn and bus will get you there in under 45 minutes at that time of day. If you're close to the S-Bahn stop, it should take 30 minutes. Check under Berlin-Verkehr.

It is not a problem at all by public transport, but if you feel more comfortable, simply call a taxi - not a problem at all either.

Public transport would be the S2 from Oranienburger Straße to Gesundbrunnen, from there the S42 to Beusselstraße and from there the TXL bus to Tegel Airport. No problem for a local, 33 minutes and 2,30, but a taxi for 17 Euro will do a similar trick.

My departure from Berlin TXL will be at 6.40 a.m. on Brussels Airlines, connecting on to the U.S. on UA. I know one doesn't need to make very early check-in times at such early hours, when nothing at the airport may be open; I think I should aim to be there at 5.

I see there are public transport options at that hour, but I think in this case I should use a taxi or car service; I guess leaving my vacation rental apartment in Mitte near the New Synagogue at 4.30? Are there any recommendations for a taxi or car service that can be arranged the day before? Can I phone in English, or can it be done online reliably?

I would also take public transport or a taxi but I would be there a little later then 5. My aim would be there between 5.15 and 5.30, if you have access to a lounge (let's say LH BIZ or SEN), I'd skip breakfast at home and take care of it in the lounge.

In the morning, every minute in bed counts ;)