Don't take the first offer they make. It's very unlikely the loss adjuster has seen the car in person and the first offer made is based on the lowest evalulation or in their parlance bottom book. As the accident isn't your fault then the amount paid out will be recovered from the other party and you ought to be paid full retail value of a similar car.
Insist that the engineer sees your car so they can properly assess the condition. List all the maintenance, options and recent expenditure to prove the condition and that your car was cared for. As the others have said provide retail priced examples of similar cars to yours to back up your case.
If there are no injuries and no hire cars to provide then there's no money in it for the insurers various partner companies, they will want the case settled quickly so if you provide the paperwork to back up your case you'll probbly find it all done in a month.