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Incorrect!

You're driving a car that has a diesel engine. What can a loose filler cap on your fuel tank cause?

It can make the engine difficult to start
It can make the roads slippery for other road users
Correct answer
It can improve your vehicle's fuel consumption
You selected this answer
It can increase the level of exhaust emissions

DVSA theory test explanation

Diesel fuel can spill out if your filler cap is not secured properly. This is most likely to occur on bends, junctions and roundabouts, where it will make the road slippery, especially if it's wet. At the end of a spell of dry weather, road surfaces may be especially slippery where diesel has been spilled but it has not been washed away by rain.

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