Thanks for that picture Matt!
Taking measurements off the screen, I make the BF:EVO figures to be about 29mm head-to-toe (the picture is about 1.14 times life-size, based on the Cadian). Discount the helmet and the soles of the boots, and that puts them at 27-28mm. Account for the stance and you're at the high end of 28mm head-to-toe, with the Arab being markedly taller.
Now to get technical...
At 1/65 scale, the 28mm tall guys work out to be 1820mm if they were 1/1, which is actually rather tall.
Working the other way around, translating 28mm to 1700mm (IMO a better average male height) would make the scale 1/60.
A 1700mm guy at 1/65 would be 26mm.
My opinion, then, is that the scale is a bit off between the infantry and the vehicles, but that it is technically quite minor. In fact, considering the vagaries of 25/28mm scaling, I would not be surprised to see you sell quite a few of these vehicles to people with existing collections of modern miniatures.
Personally I would have preferred it if the infantry had been scaled down to around 25mm, or the vehicles up to 1/60. This would leave the vehicles slightly oversized (instead of slightly undersized) which would have been good to accomodate for the fact that the minis are on bases (I love the new flatter bases, but they're still bases!).
That said, the difference is quite small and it really depends on the person whether they're cool with it. An easy fix for those who are bothered by the scale would be to mount their vehicles on 2-3mm bases as well.
