limo tipping etiquette

I suspect the answer to this question may be very subjective but interested in gauging opinion nonetheless.

So, I am currently en route to T3 for the 4.50 to JFK - my view is that it's probably unnecessary to tip my VS supplied limo driver, is that fair, or does anyone else think tipping is appropriate here?

Perhaps a more important consideration is on the US side - I do generally tip there because it's more of a cultural norm/expectation - again, is that what the rest of you would do?

I have about 30 minutes left of my journey, so quick answers to the 1st question would be appreciated!

Thanks
RC

If the driver has been pleasant and given you a good drive, I would say a £5 tip would be appropriate.

I calculate the cost of the journey if I was to pay for it, and tip normal amounts on that estimate.

This is a case that is more clearcut to me, if you tip a black cab driver, I see very little difference with the CDC driver.