What's the Point of Using [self class]

Is this code correct

@implementation Vehicle
+(id) vehicleWithColor:(NSColor*)color {
    id newInstance = [[[self class] alloc] init]; // PERFECT, the class is // dynamically identified
    [newInstance setColor:color];
    return [newInstance autorelease];
}
@end

Why use [self class]

I thought self already points to the class on static methods (the ones with +)