MENLO PARK, Calif. -- Tesla Motors has discovered something highly unusual about the way customers use their cars.

They want to make conference calls in them.

Unlike many sports cars, Tesla Roadsters are often being driven for daily commutes, according to spokesperson Rachel Konrad. Some customers have already put thousands of miles on their cars. As a result, Tesla has tweaked the design of its 2010 Roadster to accommodate both sports car enthusiasts and the everyday driver.

The closest analogy to what Tesla is trying to accomplish seems to be with Porsche. The company makes sports cars too, but owners take them out on the road more than Ferraris.

The 2010 Roadster and Roadster Sport, thus, come with chassis rails equipped with thousands of sound-dampening pellets to deaden the sound of any rattling or shaking. The car also comes with a glove compartment: earlier versions just had a shelf where you could put your sunglasses. The suspension can be shifted from race car mode (stiff, less forgiving) to standard mode (more like a Lexus).

On the sports car side of things, it is now easier to toggle between "standard" mode, where the battery can take you 250 miles or so on a charge, and performance mode, where acceleration is optimized. In the old Roadster, drivers had to reach down and touch a button on a screen. But, by the time you did that, the BMW (or Toyota Highlander) you wanted to beat out of the intersection is long gone. Now, you just turn the key forward to toggle back and forth between standard and performance mode.

The carbon fiber on the car's body is also more pronounced: Carbon accents wrap around the bumper and various cockpit components. Another nice touch: Tesla got rid of the stick shift for going from reverse to drive and put in a push-button transmission. Very Tomorrowland.

The Sport can do zero to 60 miles per hour in 3.7 seconds, or faster than the 3.9 seconds it takes the regular Roadster. Firmware included in the car's system also optimizes the acceleration. The firmware, which comes in the Sport, is probably the biggest difference between the older and the newer Roadster. (We drove the Roadster Sport.) Between zero and 20 miles an hour, it moves fairly fast, but once it hits 20 the acceleration climbs. The first time you gun it, you get thrown back in your seat at the 20 mile per hour mark.

The car also accelerates fairly rapidly on the freeway. The car does not accelerate as fast between 50 miles per hour and 80 miles per hour as it does between 30 and 60 miles an hour, but it still doesn't have much of a problem in moving up the speedometer.

At one point, we were – without first knowing it – racing an guy in a Mustang on the freeway. He eventually overtook us, but his engine was screaming and his car was emitting all sorts of mechanical smells when he passed. We were moving at just above 80 miles per hour and hadn't even fully depressed the accelerator. We didn't chase because: (1) I didn't want a ticket, and (2) I generally drive like an escapee from a retirement home. The informal race started when we were going about 65.

On nearby Skyline Boulevard, a twisting, shaded road that sits atop Silicon Valley, we had no problem keeping ahead of the guy behind us and navigating the curves. That driver, a Lockheed engineer, was in a rental car, but he told us he also built and raced drag racers in his spare time. When you drive, people stare.

The most difficult thing to get used to? The car only sits a few feet off the ground. Even a Ford Fiesta looks like and SUV.

And forget going to Trader Joe's. The trunk can only hold about three grocery bags.