Duck and cover

A last glance in the mirror shows the rider seems to be alone. You duck low in your seat, then slither out the far side of the car, pressing up against the vehicle such that you have some cover in the event of a gunfight, and listen to the engine roar closer. Hopefully the rider will just pass by, and leave you be.

A few moments later, the roaring engine's pitch changes, and you can tell the bike is rolling to a halt next to your car. Shit. You grip your pistol a little tighter, listening as the engine rumbles to a halt, then cuts out. You hear what sounds like heavy boots hit the pavement, then a slight rustling.

"I know you're back there. Come on out, real slow-like, hands in the air." The clack-clack of a shotgun's pump working punctuates his point. He doesn't sound like the friendly sort.

You're outgunned, and in an inferior position. However, maybe you can get the drop on him. There's always waiting and trying to nail him as he comes around the car, or you could just surrender and hope for the best.