Take it from someone who loves the RX7 - me!
An auto RX7 you are getting between 12-14mpg average, if you are careful, you can get nearly double that from the supra....
As you will probably be aware, the engine rebuilds on this are circa £2500, although the engine has fewer moving parts, the form of the 13B engine means you have to maintain it so much more! (how much time do you have, if you are busy, you could neglect checking the car) Supras you check the oil weekly, RX7 daily. Although you DO NOT put synthetic oil in a 13B engine, as the oil conditioners react badly to the carbon apex seals of the engine, hardening them and making them prone to failure.
The 7 is a beautiful car, make no mistake, it handles like a missile and goes like one too. I consider it to be a light sprinter, not a GT car, like the others.
7's are a bastard round town, hate low rev driving, grumble when they are driven round town - I have never driven a car with such idosynchrasies.
I trust you have done your homework, if you are going for a 7, make sure that you are getting at least 7 on the compression test, and make sure that the front and back rotor are no more than 5-10% different, they should be the same.
If you wife wants a lovely looking car, which is well mannered and a bit of a tart when she wants it to be get the SUPRA!!!!
GTO's like someone else said are expensive to repair and have a habit of eating gearboxes and transfer boxes. I did my homework, when Iw as looking at a jap sports-car, as I looked at them... The weigh about 1800kg, which is a lot! The amount of people who own Supra's on here and drive them to within of thier lives, is uncountable. The supra is such a strong, reliable car. Why did BMW fear it, when it first came out?
Sorry for my ramble, hope you find your wife a perfect car!