I think that arriving to that conclusion (that it looks like a taxi) was not meant to be mean spirited. It's just the way it is.

If you're bent on changing that image, change the color. If not, just accept the fact that it will, on occasion, gets mistaken for a taxi or a rent-a-car.

I have an associate who drives a white Corolla LE. He's quite comfortable with it that he's even the one that started bringing up the fact that he gets flagged down by unsuspecting commuters almost everyday. He even joked about that the 'LE' meant 'Low End'.

Anyway, don't worry. Just flip it around and use the situation as an ice breaker.