Since I bought the Metro in September I have spent a grand total of $3,735.72 CAD...
...of course, that includes the purchase of the car (2,300) and fuel (420.35). The other $1,015.37 has been for parts and a LOT of tools to complete various jobs that have improved the car's chances of a long life and better fuel economy.
Around $150 but I haven't installed the catch can and the PCV valve.
Aero stuff, spark plug wires, distributor cap, distributor rotor, new intake airhose, LED's, engine coolant temp sensor, tranny cooler, 1.2 bar radiator cap, and some other stuff.
I have another $120 worth of maintenance stuff laying in my closet. It's cheaper to buy the parts yourself than to go the dealer and have them put overpriced parts on the car and rape you with their labor costs. I still buy Nissan parts, just from another dealer at half the cost.
You win either way. You don't have to make the money back with the gas savings. You pratically build a car. You got another engine, tranny, a lot of a good parts from other cars. You practically have a whole different car for about 5k including purchase price of car.
Most of the things like rims/lowering I would've bought anyway.
I've spent 160 on the MID and misc. 40ish on ****, but let's think about this engine I've picked up that has enabled me to sell about 150 dollars worth of stuff, not to mention the other random **** I have been able to sell by picking things up for cheap or free. In fact, if you count my ecu work I've prolly spent almost nothing on the car besides the purchase price.
I've spent about $200 plus $125 for the Scangage. I should be able to make it back in 50k miles without much trouble.
I don't consider maint stuff like plugs, wires, fluids as fuel economy mod costs, because when you buy a 90k mi car, you need to do any maint that should have been done if you can't be sure it was done. You could argue the extra cost of using good synthetics, but I'd argue that I'd have used them anyway with an extended maint intgerval as a result to get a payback for them.