A car does Hamburg to Düsseldorf in roughly 4h 02 over 399 km. The motorway runs almost where the map does — 399 km of road across 338 km of straight line. The difference from every other way of making the trip is that it starts at your address and ends at theirs.
The fare is fixed when you book, so a closed lane or a slow stretch costs you time and not money — there is no meter and no waiting charge. Pickup is any address in Hamburg: a home, a hotel, an office, a venue. Drop-off is the exact address in Düsseldorf, not the nearest station to it. The route crosses from Hamburg into Nordrhein-Westfalen; the price covers the whole of it including tolls. The same fixed-price arrangement covers Hamburg to Paderborn, a separate route with its own measured distance.
An executive saloon on a 4h 02 run is a quiet place to work: the same car the whole way, no changes, no platform, and a driver who takes the route. Longer bookings are usually made a day or more ahead, and the return leg can be fixed at the same time and the same price. Arriving by air instead? Hamburg Airport Transfers covers every destination we serve from the airport.
Counting the whole journey, not the fast part of it
A rail time on a corridor this long is quoted platform to platform, and that stretch is the part of the day that goes well. Around it sit a local leg to the Hauptbahnhof, a margin you set yourself because the next departure is not for an hour, a change on most pairs this far apart, and another local leg at the other end with whatever you are carrying. A car quotes the whole thing instead: 4h 02 from the address you give us to the address you give us, one vehicle, one driver, nothing in between that can be missed. That does not make it faster — over 399 km it usually is not, and the comparison above says so. It makes the total knowable before you leave, which is a different property and occasionally the one that decides the booking: an early meeting, a connection at the far end, or a group whose day cannot absorb a missed change.
The two journeys a rail ticket does not include
A train time is measured Hauptbahnhof to Hauptbahnhof, and almost nobody starts or finishes at one. The real Hamburg–Düsseldorf journey by rail is usually three journeys: getting to the station with your bags, the train itself, and getting from the far station to the actual address — the last of which is a taxi at the far end, at a metered price, in a city you may not know. Those two legs are where the published time and the published fare both stop being the whole story. A private car removes them by starting and ending at the addresses instead, which is why the comparison is closer than a timetable makes it look.