While your sports car is gone, the only real comment I have for
you is to never ever put your child in further danger because
of convienience.
I would love to leave mine in my car as I spend the 30 seconds
running into the gas store to pay for gas, but I don't. I take
her out, inside, pay, put her back in. It takes more time, but
it is definitely more safe to be with me than alone in a car,
locked or not.
This is not about whether you drive the safest car possible, the
largest car, or the car with most safety features. This is about
what numerous car organizations (such as AMA), numerous car manufacturers, numerous governments (Can, USA, UK, France,
need I go on?) have found in study after study, test after test.
Your child is safest in the back seat, in an appropriate child
seat.
Your vehicle is designed for the baby seat in the back,
just as it is designed to absolutely destroy itself upon
impact with anything, at any speed, yet keeping you
and your family intact and safe inside the "cage".
There is a reason, beyond car companies making money,
for your bumper to break into a million pieces at a 10mph
"bump". (It's better for the outside of the car to take
the energy generated by the collision and destroy the
trunk, side panels, front area, and not pass it onto
the passengers. If the passengers took a major portion of
force of the hit...well...

That's why you see so many
cars that look absolutely destoryed, and you wonder how
anyone walked away. It was designed that way.)
Finally, if you really wanted to, you could hook up a child seat
into your sports car, then go down to a variety of fire halls
or police stations, and they will tell you exactly what they
think about it.
In fact, it is suggested that once you do have your child seat
picked out and installed, you can go down and they will inspect,
for free, your installation.
ers
PS. Congrats on your upcoming baby