Driving in New Jersey is pretty intense on a day to day basis. I've taken a lot of trips through the Garden State, and have to say that it's a fast pace overall, with a lot of unsteady speed segments on any of the Interstates or Garden Parkway in normal daytime driving.
The commute portions of the day are the worst of course. Best time to drive north to south or south to north is after 10 pm to about 3 or 4 am. I've only driven my Insight through NJ one time, taking it home to Maine from North Carolina.
We were able to skip the rush hour by spending the night near Philadelphia, and get a slow start in the morning. Traffic was still not what I would consider light, and since the Insight was new, I took it pretty easy on the car, varying speed as much as I could.
This car started out with the normal low car lot MID indicated MPG in the upper teens, if I recall correctly. The temperature was about 70 degrees. Our Insight was a leftover, already a year old, with minimal miles on the odometer, 10-12 if I remember. By the time we had called it a day, it was around 10 pm and had suffered the normal Washington evening commute slow go slog. MPG on the MID had climbed to the high 40s by that time. I took a picture of it while stopped on I-95 northbound before hitting the beltway.
We got home in Maine about midnight. My wife was driving our Prius, so there were stops for lunch and diner. When I pulled into my driveway that night, the MID was at 50.9 and the temperature was in the teens above zero. Calculated MPG for this first 1.5 day highway trip for a brand new Insight was just over 48 mpg. Speeds were varied as much as I could safely do, between 55-65 mph. The trip through New Jersey was the normal bumper to bumper mad rush, even with the fact that we missed the real rush hour.
After not driving the Insight a lot this quite chilly Winter, and doing a few- go nowhere battery maintenance runs- out in the driveway, the MID was down in the 30s. Once the salt and sand was off the roads, I've driven the Insight a few times since late March. Today I had to do some errands and drove about 65 miles. I'm still burning down a Winter gas fill from December, and the MID is back to 50.6 today. Closing in on 5,000 miles.
MPG is totally dependent on Temperature, Driving Style, Tire Type, Tire Pressure, Topography, Load in the Car and Traffic Density. Last Summer, my measured (not MID) local rural driving with a bicycle hanging off the back of the car most times was 50 to 55 mpg. We have hills, but the pace on our roads here is pretty laid back and traffic, compared to New Jersey's high density City areas, is very light. Rural speed limits vary from 25 mph to 55 mph.
If you commute and give yourself the least possible time to get to work, MPG will be somewhat lower than if you leave a little more time to get to work and are able to take it a little easier. Even 10 minutes extra can ease the driving tension significantly and allow better MPG. I can get over 55 mpg at 40 to 50 mph. Can't do that going 75 mph on the Interstate and hustling to make the next traffic light in city stop and go. Any car, Hybrid, Electric, Gasoline, Diesel, Natural Gas, or Dilithium powered will show the same economy characteristics.