Hyundai Tucson Signature 2.0 AWD AT Diesel

I recently purchased a used Hyundai Tuscon with 18,00 miles. I had looked at a Soul, Rogue, Sportage and CR-V. While the CR-V was the nicest, it was also the most expensive and budget was a major factor for me. After much internet research on these vehicles and others in the small SUV category and the 2017 range, I identified the cars mentioned above to test drive. I chose the Tuscon due to its overall good condition and low mileage, yet the four cylinder engine seems to fight to maintain speeds over 50 mph., while the ride is stiff yet relatively secure. The handling is responsive but for some reason I feel as if I am driving a large go-cart. While environmentally conscious, I didn't want a 6 cylinder vehicle although I knew of the overall benefits of a 6 vs. a 4 in terms of a better highway ride experience. Perhaps if the Tuscon had a higher performing 4 cylinder I wouldn't be writing this for future potential Tuscon buyers. Maybe the later models have addressed the audible engine strain at higher speeds. Additionally, the millisecond you take your foot off of the gas pedal the car de-accelerates considerably, which is annoying in my book. I'd like a little glide.