Which executive car has the lowest motorway road noise?

Can you tell me which executive car is the quietest to be in when cruising on the motorway?

Asked on 29 November 2016 by simon quarrell

Answered by Honest John
Mercedes-Benz S500 petrol PHEV hybrid: www.honestjohn.co.uk/road-tests/mercedes-benz/merc.../ But noter that the Government plug in hybrid grant has now been reduced from the figures in the test.
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Supremely comfortable with an elegant yet modern interior., handles impressively well for such a big car, reasonable economy and emissions.