It's a flaw in 2142 that doesn't give an option in the menu.  In one of the settings  .con files inside the battlefield 2142 folder in /my documents/  you'll find the control key mappings.  You can manually change it in there.

But to respond to the earlier point, a couple problems occur with making the ships faster:

Firstly, dogfighting becomes a huge amount harder.  Unlike other games/mods in 2/2142 we don't rely on heatseeking missiles but straightshot blasters.  As such our weapons are affected much more heavily by the realities of lag and delay across the internet. You'll have noticed this if you ever see your shots hitting a craft but not doing damage.  Speeding up the ships would only make it worse.  And this isn't even taking into account the difficulties of maneuverability and instability that many of our spacecraft encounter at higher speeds in this engine.

And secondly, the engine only supports maps so big.  We already sport extremely large space maps-even more grand when compared to any ground map.  You could fit 64 Endor Strike Team maps on the floor of any one of our space maps, and if you stacked them vertically at 1km intervals you could get 512 of them in the standard area of engagement.  Try walking from one side of Endor Strike team to the other without a speederbike, then imagine doing that 8 times over and that's one side of any space map.  Now try flying an x-wing or a-wing down the side of Taloraan and realise just how fast they are going compared to you walking and hopefully you'll get some sense of how big our maps are.

Our ships are balanced well against the massive distances they have to cross.  If we made them faster we'd have to make the distances greater to maintain that same balance, which would both be impossible in the engine and also not change what you want in the first place.  And since we can't make the maps bigger if you crossed 1.6km in a few seconds then you'd hit the edge of our current maps within 5 seconds.  The game would consist of nothing more than flying back and forth trying not to go out of bounds every couple seconds.

As such I'm not really sure what would be accomplished with making the ships faster other than to say they're faster.  I'll admit the current ones aren't 100% perfect but they're definitely playable and do the job well

Fear the Woodzilla