Kirkcaldy based - I head through to Glasgow relatively often, with my most recent trip being this coming Tuesday. Still relatively new to driving so not too clued up on local 'hacks' on how to get around efficiently.

With the cost of living and petrol going up, I want to try and make every last drop of my petrol count.

An 'easy' route would be crossing the bridge and taking the motorway across. Google Maps is showing me a 27% fuel efficiency saving by taking the Rosyth junction on the M90, the A985 to Kincardine and then taking the M876/M80 to Glasgow.

Has anyone done this before and noticed real world savings in terms of their petrol or mpg returned?

I know motorways can be the most fuel efficient due to their constant speeds etc, so I'm wondering if because the A985 is not a 70mph road, that's how the savings have been calculated and they'd be negligible if I did 60mph on the motorway rather than the limit.

Thanks everyone!

Edited a couple times for clarity.