Nearly new is usually.a higher monthly.payment than new.
But this isn't right. Buying a new car for 18K, or the same model a year older for 12K.
In two years time, your £18K is worth 9K, perhaps. In 2 years time, your nearly new is worth 6K perhaps. So the new one costs you 9K in depreciation, compared with 6K plus finance costs on a larger figure.
If you get a lower priced deal, you are losing it somewhere along the line - eg, at the other end in the residual.
If you are in secure employment, it's might be a matter of taste, as to whether the cachet of a "new" car is worth the extra - but don't pretend the new car is, in general, less expensive that the used one.
It's still the opportunity cost. The extra money spent on a dearer car is the holiday/tv/home improvement you can't afford now.
And if you do buy the car outright, rather than lease, then at the end of the period you OWN a 3/4year old car that you could keep for another year at NO cost, other than the lower trade-in value for the extra year, and the extra depreciation is going to be a lot loss than first year depreciation on he new car.