Yes, the key lies in the definition of "a few", which is simply "more than 2 but not many."
A Few is also often compared with or interchangeable with "a handful" which would mean 5ish or so.
But 'a few' can mean more, too... such as when 'a few' are coming to the wedding itself, but 50 to the reception. 'A Few' here could even be a dozen.
So many possibilities are at hand.
We know
Gandalf said to
Gwaihir they needed to 'outmatch the wings of the
Nazgûl' when going to get
Frodo.
If we want to get literal, a Bald Eagle can readh 75 - 99 mph, a red-tailed hawk 120 mph and a Golden Eagle has clocked at 200 mph.
So a great number of speeds and variations are available given Gwaihir and buddies are fantastical to begin with.
But the 3 hours at 196.66 mph is apparently not unreasonable.
And
@Deimos' comment is well-taken. Gandalf is generalizing...bringing a bit of perspective into their situation.