1. Weight
2. Aereodinamics
3. Low power (240's are NOT sports cars!!!)

What I have done to reduce or improve this 3 areas

1. Remove all sound padding from the interiors, if needed, replace it with lightweight insulation (at least I have done this on the roof)
Keep your car free of stuff. Carry only the necessary things!!. Theres no need for that 20 pound toolbox in the trunk!!

2. Use the lower engine cover. Not only helps reduce the drag, also helps to cool the engine and protect it from the elements!! Also lower your car with springs. The less air under your car, better!!

3. Power....well power (HP and torque) needs more fuel, but, what if we make our engines more efficient? Low restriction air filter and exhaust, synth fluids, electric fans, headers...etc
Also, mantain your ignition system in top notch, dunno is a high powered coil will help here though. Use good tires, dont use bigger tires. Not only are bigger, screw up your ratios, but also creates more drag!!
Aligment and suspension. Our cars loves curves, treat them correctly and use some good stuff here. A misaligned car not only wear tires faster, creates DRAG!!

There is a lot of potential on these cars. I have another car with the same engine size and I am amazed how much power difference is between the 2 (Nissan 240sx 2.4 I-4 engine) Although comparing the two is no justice, in any area above, why dont you try to squeeze all the hidden potential there!!.