Q. My 2015 Nissan X-Trail will not shift into seventh gear in automatic mode, which I think is reducing the fuel economy. Why?
PS, Horsham, West Sussex
A. According to Nissan, the car shifts into seventh gear automatically at about 80-85mph (German autobahn speeds). The engine is turbocharged, and because the turbo is driven by exhaust gas, the engine needs to run at a reasonable speed to keep the charger spinning properly. In the X-Trail, Nissan says, an engine speed above 2,000rpm is best for fuel efficiency. At 70mph, engine speed would be less than 2,000rpm in seventh, so the gearbox stays in sixth.
TIM’LL FIX IT
Tim Shallcross used to train AA patrols to fix cars. Now he advises the Institute of Advanced Motoring — read more from Tim here.
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