Sonic the Hedgehog 1: 1991
 
Friendship is Magic Part 1: 2010
 
My Conclusion: Sonic has much more experience with high speed death races than Rainbow Dash.

@Background Pony #93E7  
Also the time of around 3-5 more episodes coming out to the time making the death battle in the first place.
 
Kind of like how that line “There are no machines for Star Scream to take over but a sewing machine” was made.

I wounder how much stamina they have…

@Zennistrad  
Sorry, but as of the more recent games and the manuals, Sonic’s speed is confirmed to be around-or-above hypersonic in nature, clocking up to a maximum of Mach 10 or Mach 11.
 
@Background Pony  
The problem with Death Battle is that their math is usually invariably faulty, or just outright wrong. Metal Sonic’s actually capable of matching Sonic’s speed, usually through receiving regular upgrades (such as the ones he received in Sonic 4: Episode II). Meanwhile, the supposed speed data for Rainbow Dash that was used by Death Battle was not only readjusted by someone else using that same formula to place her slowly below Mach 5, but then someone else came around and did it even more efficiently, and clearly, which resulted in Rainbow Dash’s top speed actually being just barely around Mach 1.2 to Mach 2 at the very highest.
 
In short: Dash is outclassed in speed and stamina alike.

@Vree  
Also, the phrase is “I don’t have any thumbs.”

According to Death Battle, Metal Sonic and Rainbow Dash have the same max speed of Mach 5. The problem is, Metal Sonic can reach that speed on the surface of the planet, while Dash does it in the air, meaning Metal Sonic is technically faster as Mach speeds are harder to achieve on the ground. Plus, as said earlier, it seems Dash can only reach her max briefly. Guess both Sonics outclass can Rainbow Dash.

I can’t…I don’t got no thumbs!

Sonic’s top speed has never been measured.
 
If I recall correctly, in the Archie comics he ran halfway around Mobius (which is roughly the size of Earth) in five seconds, to save a friend from Eggman’s clutches after a diabolical plan that lured Sonic to the very edge of lava reef zone.
 
Halfway around the world.
 
Five seconds.
 
1/2 circumference of Earth: 12,450.5 Miles.
 
Sonic was running at about 8,964,360 miles per hour.
 
Given the approx. Speed of Sound at sea level = 761 mph…
 
Sonic was running at Mach 11,779.
 
Dash, you’ve been outclassed. :P

DAT bravery! <3

No fair!  
Those guys got rocket packs!  
ROCKET PACKS!

Here’s some more music.
 
And, bonus stuff

Then they all fucked.
 
The end.

Sonic’s top speed in his normal form is only slightly faster than Mach 1, so he might not be as fast as Dash.
 
However, it’s been shown that he’s capable of running at mach speed for several hours on end, and can bring himself to a full stop instantly with little effort.

@Yorec  
Nice~
 
@Everyone Else  
I guess that’s true. She’s probably not got as much endurance. She’s more of a sprinter I guess.

well sonic was running even before year 2000 so i guess he has some more resistance after all
 
even if rd is faster she probly would get tired faster i guess…

To be fair, while Dash might arguably be faster according to the Ponybase, I highly doubt she’d be able to maintain a constant top speed towards the end of an endurance race like Sonic has. The guy’s raced around the multiverse at top speed and didn’t slow down.
 
We don’t know RD’s limit, but it probably won’t measure, seeing as she had to work her best to keep up with Applejack.

Sonic you’re much better than me in every way! Also, I can’t keep going.

…Dash is faster than that.