Vettel ran out of fuel in Bahrain
Initially after the 22-year-old pole sitter gave up the lead of the race to the eventual three podium-getters, Red Bull diagnosed an exhaust problem.
A subsequent media statement clarified that it was actually a spark plug problem within the Renault engine that was the matter, but Spain's AS newspaper reported last week that Vettel simply slowed to prevent running out of fuel.
"The lap times dropped so rapidly that one can imagine the electronic control unit (ECU) switching to a conservative program to save fuel," Dennis is quoted as saying in a report of the Cologne newspaper Express.
Briton Dennis is the chairman and a 15 per cent shareholder of McLaren Group, whose subsidiary McLaren Electronic Systems (MES) supplies the control ECU run mandatorily by all F1 teams.
The 62-year-old was speaking late last week at the launch of McLaren's new MP4-12C production supercar.
His theory would explain how Vettel's RB6, having perhaps conserved enough fuel for a final surge, was able to record fully competitive times in the final laps to prevent Nico Rosberg from passing.
During Dennis' long reign as McLaren team boss, Adrian Newey worked for a long time with the British team. And Newey, the main author of the RB6, is renowned for pushing the envelope with his F1 designs.
"The problem with the Red Bull could be design," Dennis continued.
"It could be the fuel tank is too small, or the fuel consumption is higher than they expected," he added.
Renault's engine boss Rob White told Express that the French marque has also been analyzing the cause of Vettel's Bahrain problem.
"The investigation to identify the reason for Vettel's engine problem is ongoing," he said.
"A problem with the spark plug was found, but we have no reason to suspect a defect in the component itself."