Engine revs but car moves slowly as if a bad transmission. Only happens in forward, reverse is fine. Dashboard indicator light (gear with an exclamation point) is on. Mechanic says it needs another transmission but I think it’s more electronic than mechanical. Any comments?
Every foot that you drive the car in this condition makes it more and more likely that you will have destroyed the friction surfaces in the transmission.
At the first sign of this type of symptom, the trans fluid level, color and smell should have been checked, and if adding/changing fluid did not help, then the car should have been immediately flat-bedded to an independent transmission shop for evaluation.
Do not continue to drive the car–even for a few feet–unless you want to ensure that it will need a new transmission.
You can’t get a better answer then above except you probable can drive it there.