What do you think of the automatic gearboxes in the B-Class, A3 and Golf?

My shortlist of new cars is down to three: Mercedes-Benz B-Class, Audi A3 and Volkswagen Golf, all with automatic gearboxes. I am aware of your reviews that rate highly the latter two, but I also see a lot of reader reports about issues with their automatic gearboxes that I understand are identical. I like the Mercedes for its higher seating and (so easier access) and because it's roomier, but do the same issues afflict the Mercedes 7-speed gearbox?

Asked on 11 May 2013 by DW, Knutsford

Answered by Honest John
They all have 7-speed dual clutch transmissions and are comparatively fuel efficient, but there is an important difference between VAG’s DSG/S-tronic and the Mercedes-Benz system. VAG insists on an interlock forcing you to press the brake pedal before you can move the lever from N to D and this is not only irritating, it causes another problem. The brake light switch sends a signal to the ECU that the brakes are applied and as a result the ECU cuts power. The problem is that this signal can be delayed, so you can emerge from a side road on the fuel in the combustion chamber, then, halfway across the road, power is cut and you can be stranded for a second or two before the system self corrects. With the Mercedes system the lever can be moved from N to D without pressing the brake pedal. Ford and Volvo fit Getrag Powershift Dual Clutch transmissions and, again these have no interlock between N and D.
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