They say that honesty is the best policy. It's also said that the truth can hurt.

Ford is experiencing both of these with its C-Max Hybrid--with lower sales since the company dropped its official EPA-rated mileage figures.

The C-Max Hybrid was launched to great fanfare in 2012, touting EPA combined mileage of 47 mpg.

That matched Ford's larger, sleeker Fusion Hybrid, and beat the Toyota Prius V's 42 mpg combined rating.

It soon became apparent though that journalists and owners alike were struggling to replicate the lofty mileage claims, with figures in the high-30s not uncommon.

Our own gas-mileage test, which typically returns results close to EPA figures, resulted in a figure of just under 40 mpg. Previous drivers hadn't been so lucky--its lifetime display showed just 33.4 mpg.

MORE: EPA's Ford C-Max Hybrid Gas Mileage: "Our Testing Not At Fault"

Ford initially put the low mileage reports down to driving style. The C-Max Hybrid has a much sportier drivetrain setup than its Prius V rival, and Ford reasoned that drivers enjoying the power are far less likely to hit official numbers.

That's a fair enough assessment, but couldn't explain why mileage in even careful driving struggled to match the EPA-rated figures.

Soon after, the cause of the problem was revealed: A loophole in EPA testing requirements means automakers can carry over results from other vehicles in the same weight class, with the same powertrain, to save testing costs.

Ford had used the Fusion Hybrid's figures--as a similar vehicle--which resulted in figures higher than were realistic for the C-Max.

MUST READ: Ford's C-Max Mileage Mess: How It Happened And What It Means

The company subsequently tested the C-Max separately, to get its current 43 mpg figure.

But speaking to The Detroit News, Ford executive Joe Hinrichs confirmed that the mileage revision has hurt sales.

As well as having to compensate owners for the cars' poorer-than-expected economy, sales of the C-Max fell 39 percent in March, and are down 43 percent for the year.

Those still buying the C-Max are no doubt enjoying their cars, and achieving mileage much closer to the official 43 mpg figure. That's still higher than the Prius V, incidentally.

But the truth has hurt for Ford--the C-Max is no longer quite as attractive to its intended customers as the 47 mpg rating made it look.


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