I was told when buying my first new car that a V6 would be nice for driving on interstates, etc. I loved having the extra power and I can definately tell the difference when driving a rental car with a 4 cylinder. I doubt I will ever buy a car without a V6.
Don't limit yourself or judge all motors on rental cars. I've had everything from a 100 horsepower 4cyl to a 500 horsepower 427 V8 and there are both good and bad engines with each type of engine. I'd take the 200hp turbocharged 4cyl in my VW GTI over the 350 I had in a monte carlo, the 6 cyl I had in a fiero gt, etc.
I've only had one truly underpowered vehicle and that was a first year Honda CRV that you had to really wring out to get above 80 mph. It was actually more of a gearing issue than a lack of power.
What a lot of people don't realize is that it's common for family cars of today to run 14 second 1/4 miles. This is faster than those Trans Ams that were in Smokey and the Bandit and had 400 cubic inch engines.
A Subura WRX with a turbocharged flat four will be knocking on the door of a legendary Chevelle LS6 with 450hp in the 1/4 mile and will flat out kill it 0-60.