Here are my criteria:
* Must be able to reach foot pedals. She is less than 5’ tall, and cannot operate most minivans.
* Decent gas mileage (26+ highway)
* Roomy. Must transport kids + dorm junk to and from colleges.
* Cannot afford anything brand new
I have a colleague who just retired and she is about 5’ tall. She commuted about 25 miles to campus in a Pontiac Vibe. However,during harvest season,I’ve seen this person drive a big grain truck to campus and go in and teach her classes.
Have your wife try on a vehicles for size and give vehicles that seem comfortable a lengthy test drive. For me, buying a car is akin to buying a pair of shoes–comfort comes first.
I would say something like the Toyota Matrix/Pontiac Vibe or Mazda 5.
Why not get pedal extenders and let her pick from any vehicle she likes? Here’s one place, I’m sure they are others http://www.pedalextenders.com/
You gave us your criteria. What are your wife’s criteria?
Get what SHE wants or you will pay for years!!!
Some vehicles have had electrically-adjustable brake and gas pedals for a few years. This feature may widen your choice of vehicles.
My SIL is 5-feet tall. She drove a Crysler Town and Country minivan and now drives a Kia Rondo. My experience last weekend indicates that you want a minivan to transport kids to college. We have an extended wheelbase minivan and removed the back row. We just barely fit everything in.
Thanks to all for the tips. In response to the many comments:
- the criteria come from my wife, not from me. I’ve wasted enough time listening to the show to know that my wife’s criteria need to drive the choice of her vehicle!
- whenever we’ve rented a minivan and she has sat in the driver’s seat, she has not been able to find a position where she was comfortable reaching the pedals.
- the pedal extenders look very interesting, in that they would seem to give us the ability to select a vehicle (such as a minivan) without worrying about her reaching the pedals. Just get the right vehicle based on size and mileage, and install the extenders.
Some vehicles have pedals that move for short or tall people. If you check out cars.com, edmunds.com, or vehix.com, you should find some. I’m sure that some minivans offer it.
My wife is about the same height (she would never admit how tall she is, so that is why ~) and she drives a Caravan very comfortably. She pulls the seat all the way fwd. I know some series of the Taurus used to have electrically adjustable pedals, so I am sure there would be more out there.
The Ford Windstar offered electrically adjustable pedals. I know that they were available in the 2002 model. My university had a couple of these in its fleet and I drove one 800 miles and back to a conference. I don’t think the gasoline mileage was the 26 mpg that the OP wants, however.
I suggested that yesterday, and the OP did not seem to be interested in this feature.
Hmm, sorry I seem to have missed this possibility in my earlier reply to everyone. I’ll check out edmunds.com, cars.com, and vehix.com to see which minivans have the adjustable pedals.
We’ve tried a Caravan and it doesn’t work for my beautiful but vertically-challenged beloved. 
Our 2005 Chev Malibu had power adjustable pedals as well as a tilt and I believe, telescoping steering wheel. It had a roomy trunk but you might want to look for a Malibu Maxx wagon of that year. Ours had no recalls for as long as we owned it and needed no repairs, warranty or otherwise. It had a gas mileage computer that read about a mile per gallon high at 32 mpg overall driving on a long trip with some city driving. It had a V6 engine with plenty of power.
If you have more stuff than the car can hold, consider one of those inexpensive $250 lightweight trailer kits for occasional use. A cartop carrier pod is another option.