I used the sports car as a frame of reference for movement speed, not acceleration speed. Human acceleration speed is wildly different from car because we're less than a 10th the weight, and a totally different shape. Wind and shit, come on man.

As well, we're still talking about low tier supers. We're not talking about normals. At twice the speed of Usain bolt, you could dodge a bullet at 500 feet.

At the tiers being presented here, low and lower end intermediate, dodging a bullet is not only a feasible feat, it's fairly easy for a balanced speed and strength character. Let's mark this down as someone who's speed class is exactly at the end of Low Tier, so he's being pushed into the lower Echelons of Intermediate because he has different stats.

He's got a movement speed of 300 mph, with an acceleration of around. . .Gimme a sec.

117.6 meters per second. Alternatively 263.06 mph.

There's your bare bones lower end intermediate Speedster, and the only thing barring him from low tier is a few mph over the limit, and a few other stats.

If I were to totally concoct a character to match the exact stats required to make guns wildly useless, they would still be a low tier.

Guns CAN be low tier.

Guns CAN be high tier.

It just depends on who's using it, and what the caliber is.