E-torx suffers from a design standard which makes several socket sizes too large for the fastener they are engaging. For instance, E10 is common on m6x1 thread bolts. Which, if they had a 6-point head, would be 10mm heads typically. No reason they should be a 3/8 socket, and yet....
As another member stated, 12 point SAE has coverage to some e-torx. Very nice trick to know. Getting 8/10/12 in 1/4 drive is a must. E-torx wrenches are less useful, as they are akin to a 6 point box end, and thus have swing arc issues. IMO an impact style 1/4 swivel joint, wobble extensions, and the 3 1/4 sockets I listed will get you quite far into a benz engine bay.
Try pricing some snap-on e-torx universals if you want some sticker shock. The low profile torx from SO combined with a wobble extension will get you into so tight areas.