I know the feeling. But I get the opportunity to drive some cars that come in or come back from detail, and then get serviced.
At first, it was the thrill of driving the Lexuses. Heck, one customer implied I should drive his SC430, top down, along the beach, since he had time to kill until he could pick up his car at home. He stated that I should drive slowly, rather than fast, along the beach-hugging route of A1A down here. Needless to say, it was a great feeling.
On the other hand, you get jaded driving the same types of cars everyday. So when the opportunity comes to drive something different, I've driven all sorts of stuff from the RSX Type S, S2000 an '01 WRX (sold the same day, unfortunately), TT quattro, BMWs, Mercedes, and a few other oddities. But sometimes you get an opportunity and you just race, er, run with it.
One day, I had to drive a car to another Lexus dealer, since the flatbed truck was out of the way. I figured it was just another ES330, but I could have used a break because we slowed down that afternoon. But it was not a Lexus, it was another brand; an AMG sedan. I really just thought it was a slightly-tuned E-class, with 300hp or so. No, it was the 469 hp, loads of torque, serious as a kick in the balls E55 version.
At one point, I floored at a stoplight, scorching an older 8-series BMW without trying. Heh, this could be fun. I might not return to work, or deliver this car. I just might run away forever, and nobody would know. Man, was I turning evil. But I remember that there's food to be put on the table, a wife that misses me, and a career to consider before committing GTA.
Although I did go back in an IS300, never in my life did a Lexus seem so...minor league. Returning to my Corolla just seemed so...public transportation. I raced the CLK Touring Car in GT3 when I got home that night and forgot my "troubles".