Your petrol car is only going to fall further in value and desirability, it also costs a lot to run in terms of fuel and motor tax, petrol cars are unloved, 75% of all new car sales in January were diesel, whilst your car is fun to drive pretty much all 2.0 ltr diesels will give you all the torque and fun you need.
I recently downsized from a 520 D auto, the new model, I hated doing it but could not justify the cost of holding it with only 8000 miles a year, I changed into a Passat 2.0 Ltr tdi with 140 bhp and banked the cash difference, this 2.0 bluemotion diesel is just terrific, VW claim nearly 70 mpg, my tax is €200 annually and insurance less than €300, my motoring costs have fallen and I have a car than is fun to drive, modern and economical, what is more is that they will be a good residual seller.
I would change your car and go diesel, Dublin to Cork crusing will hardly move the fuel indicator, whilst I am not doing the mileage to justify diesel I like the torque, you will save money and will sell it in 2016 easier than a 2.0 ltr petrol any make any model, change it ahead of your final loan repayment if possible.