Doing 400 miles a week for your regular job, I'd stay in a car that get 40+ mpg hwy.
I really like my Elantra, they can be had with 6 speed manual. My son go 50+ indicated mpg on the drive home from the dealer with the auto. I used it for work for a few days in December, it was only a 4 gallon fill but got 49 mpg. I've been driving the 2010 cobalt lately and driving similar to the Elantra in December and best tank is 33.
https://www.cars.com/vehicledetail/d...5957/overview/