But which.is fastest, and the most.complete, usable car?
Faster....
On a race course? Viper.
On a drag strip? Demon.
As I said, very different types of fast. My particular Viper is also an oddity (one of 9 HP Arrow cars built) so it feels much more 'raw' vs a standard Viper (of any generation). It's a manual, has headers, a wilder cam, an aggressive ECU tune, and it just feels much more like our '60s HP rides. Honestly, the Demon is docile in comparison, unless you put your foot into it and it wakes up, right quick!
If you had to drive either to work every day, in traffic, you definitely go with the Demon. If you want a car that FEELS like you're going 100mph at 100mph you definitely take the Viper.
Oh, and the Viper cockpit might as well be an oven. HOT AF in that cabin if you are running it hard for 30 min or more...even with AC cranking!
As I've said many times, I LOVE both of 'em. And you can lose either one of them in a heartbeat if you don't respect their power.