No mods except replacing the spark plugs and fixing a few odd things.
I do a regular route of 50 miles to visit my son twice a week and I've estimated that I spend at least 20% of the drive with the engine off.
There's 3 sections where I glide for over half a mile without power and the rest of the time I'm doing P&G. I've also trained myself to turn off the engine as soon as I see the lights ahead of me change to red OR even if I expect them to change to red. The times I drive are also very light in traffic and I've worked out a route that allows for the most favourable driving conditions [fewest lights, best roads etc] Also as an incentive I only put 10 litres in the tank so I know mentally that I HAVE to make it last 200km to get close to 50mpg US. I did use the A/C a lot the other week and only got 160km out of the 10L, YIKES ! I had no idea it made that much difference
I also change gears REALLY early to keep the revs under 2500 and as soon as I get up to 37mph in fifth gear I start doing P&G. THere's about 5km of 62mph zone in which I don't exceed 50. If there's a big long bunch of cars I pull over to let them all go past [45secs] then I have the road to myself to go as slow as I like. I find it hard to P&G properly when there's a lot of cars on the road, I have to keep checking the rear view mirror too much to relax.
Relaxing is the other BIG deal about driving like this, I actually enjoy driving now. I can happily sit at a red light for 3 mins because I KNOW it isn't costing me a cent, just a little time
And yes, smaller, car weighs 2700lbs. Or 2920 with me behind the wheel LOL