Firstly, the income tax claim of 2/3 is presumably a calculation by you or your accountant to allow for 1/3 personal use of the vehicle ( assuming it's your only mode of transport ) If you replace that with any other form of transport , car, jeep or whatever, if it's still your only mode of transport then there would still be some disallowance for personal use of possibly again, 1/3.
Secondly, the writing down of the vehicle itself is restricted to a maximum of €24,000 if the vehicle is classed as having accommodation for rear passengers, e.g., car, estate, 4 wheel drive etc. If there are no provisions for rear passengers, i.e. a proper commercial jeep or van etc., then that restriction on the capital cost does not apply.
Thirdly, if you are VAT registered ( as some farmers are ) then you cannot claim the VAT on a car/estate with rear passenger capability but you can on a commercial van/jeep etc. SUBJECT again to the first point, that if it's your only mode of transport then there would be a restriction on the VAT claim too to whatever percentage, such as the 2/3 you are presently using is deemed fair for business use. VAT on the appropriate percentage of diesel would also be allowable )
If in doubt consult your accountant if you have one or
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