It makes most sense for two couples who want to travel together in one car, or for parents with teenage children. Unlike the 2+2 convertibles available for car hire at Masons, this one has proper rear seats for adults. M xDrive all-wheel drive also helps when a summer storm catches you on the way and the road stays wet.

What the M4 Cabrio is good for

A typical summer weekend runs like this: two couples leave Prague on Saturday morning, keep the roof open on country roads and close it on the motorway so they can talk without raising their voices. They spend the night at a guesthouse in South Bohemia and are back on Sunday evening. Nobody has to follow in a second car; just pack the luggage in soft bags.

The second common reason is a trip to the water. Lake Mácha (Máchovo jezero) near Doksy works as a day trip: leave in the morning, spend the afternoon on the beach, drive back in the evening with the roof down. Towels, a blanket and a cool bag fit in the boot easily. In July and August set off early, as the beach car parks fill up fast on hot days.

The third scenario is an evening in Prague. After dinner you pick up friends outside a restaurant, open the roof and drive along the Old Town embankment of the Vltava, with the floodlit Prague Castle across the river. The heated seats are welcome once it cools down after ten. In a car this wide, give the narrow lanes of Malá Strana, the Lesser Town, a miss; the embankments and wider streets are enough for an evening drive.

In practice: seats, luggage and drive

Up front there are heated M sports seats, and in the back two individual seats where adults can comfortably manage the drive to South Bohemia. The folded roof is stowed in the boot and takes up part of it, so with four people plan on one soft bag each rather than hard suitcases. The roof works at the press of a button, so you can close it during a passing shower without getting out.

M xDrive has three modes: 4WD, 4WD Sport and 2WD. In the wet, and in spring and autumn, stay in 4WD, which sends power to both axles; you will not need 2WD on public roads. The car is wide, and in the centre's old underground garages the 360° camera shows the pillars and kerbs all around you. Set the adaptive M suspension to comfort in town; you will notice the difference on the cobbles. Under the bonnet is the S58 twin-turbo petrol straight-six with 530 hp. Phone navigation runs through Apple CarPlay or Android Auto, music through the Harman Kardon system.

Where to take the M4 Cabrio from Prague

The Třeboň region (Třeboňsko) is about 2 hours from Prague via Benešov and Tábor; drive this stretch with the roof closed. Past Veselí nad Lužnicí the land flattens out and the road runs between fishponds, meadows and tree-lined avenues, which is where the roof can come down. In Třeboň, park outside the historic core, walk across the square and through the château park, and follow part of the shore of the Svět pond; the Rožmberk pond dam is a few minutes away by car. In the afternoon, continue to Chlum u Třeboně, with a beach on the Hejtman pond and a small château. With four on board, these flat, quiet roads beat mountain hairpins: there is less wind at lower speeds, and those in the back can chat with those in front.

M4 Cabrio or Porsche 911 Cabrio?

It mostly comes down to numbers. Take the M4 Cabrio when there are three or four of you, when you are carrying more luggage or when the weather looks changeable and all-wheel drive will be welcome. The Porsche 911 Cabrio is an open car for two: the rear seats are really for bags, luggage goes in the front boot and only the rear wheels are driven. It is more compact and suits a weekend for two or an anniversary. As soon as another couple joins, go for the BMW.