In the sense that both were built for local stopping services. The Class 101 (like most if not all Modernization Plan DMUs) did use engines and BL semi-automatic transmissions from 'busses IIRC. I think the Pacers take too much flak. They were meant to be cheap to build and run and, after some teething problems, they fulfilled that brief keeping some lines and services viable that could have closed otherwise. There's some mockery about it's underpinnings being adapted from a freight chassis but that chassis is HSFV-1 (high speed freight vehicle)- among the fruits of a research project to improve stability as freight trains got faster. It was successfully tested at over 100mph on track and over 140mph on rollers so... result! Much of the data was also used in the design of the APT- indeed the projects shared some key members.