Nope, normal speed
That’s just how quick the little car was. The car might be a little faster than it was originally, as the h-bridges are FET based, rather than BJTs, so it could be getting a little extra voltage off the stock battery pack.
Great Robot, Great Speed !
Now that’s a FAST robot 
NMIH-0050 h-bridges
These are made at New Micros, and have a header at one end for logic power, an A input and a B input like the L293D you have, and also an added “not A” pin (to be jumpered to the B pin, for using a single PWM for locked antiphase drive) and an error output. There is also a header that has one input, logic power and ground like servo wires in the middle. The end has screw terminals for motor power and ground and the 2 outputs to hook up the motor. There are a number of LEDs on the board to indicate power, inputs, and outputs and they look pretty cool on a robot in the dark. And it’s all wrapped up in a big heatsink normally, except I switched it out for a smaller set on Rebounder. The main driver on the h-bridge is an Infineon TLE5206 (-2 or -2S I think). It’s got a lot of cool protections and features on it.
One note, there is no enable pin on these, so your processor may need power on operation with the PWM either high or low, or at a 50% PWM duty cycle if using locked antiphase drive to prevent movement.
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Not sure
It initially was built for an indoor competition, for 1 event called “Quick Trip”. That was just a 16 foot out and back contest. And the robot was almost too fast for it, but did good enough. Outdoor robot competitions were proposed, and so the compass was added to Rebounder (ok, not so original name), but something was weird with my code (from the night before the competition) and so it did not function well.
There is some problems in getting it to move at a lower PWM duty cycle, a sort of narrow band of PWM rates it will function at. If the on time is much below 85% duty, the robot can’t move. I need to play with PWM frequencies (some motors function better at other PWM rates, using 20 kHz). I had planned on a couple Sharp sensors, but the robot probably moves 2-3" by the time a new reading comes in, plus the inertia requires a longer distance sensor. Probably some Maxbotic sonars, and some method of wheel encoders might be added, after playing with the PWM duty/frequency some. For now, it is just going to have fun doing zippy little preprogrammed dances. You should see the grins on little kids faces when they push the button and make it go. (Some at public robot events here)
Lovelly!!! Thanks for the
Lovelly!!! Thanks for the explanation!!!
This will go to my ‘Parts I Want’ List!!! In High Priority 
I will try SN754410 soon, I´m curious to see how it behaves , and to compare it´s performance against the L293D.
Added the IsoMax program running on Rebounder
It’s the Spindance.txt file attached to the description.