Since 20 years at least modern passenger cars require technologies to broadcast local acquired data. The most popular communication media are electrical two-wire cables. Examples are shielded, unshielded, coated or uncoated twisted pair cables. Baseband modulating communication protocols like CAN and FlexRay (TM) are used mostly. The paper points out two aspects of serial communication in cars when using two-wire cables: on one hand typical bit-shape distortions appearing in time-domain measures and simulations; on the other hand the effect of these bit-shapes to a dedicated FlexRay (TM) timing parameter.