I used to commute in the north between two mid-sized cities, and any time I checked taking the car instead of the combined bike+rail travel would not have been faster, only much more inconvenient and more expensive (parking costs a lot, and not always easy to find...).
Today we have e-bikes and scooters, so hilly terrain is not a problem anymore. What I do think IS a problem is driving is still way too cheap in the UK, compared to other transportation methods.