...requirement.? Would it be ok to use regular 87 octane gas instead of premium 92 octane? What are the ramifications of using lesser grade fuel? Can I do this every time I fill up or only recommended only once in a while?
The difference between fuel grades is the percent of pure octane which they contain. Lower octane fuels self ignite (before the spark plug fires) at a lower pressure. Since the 2.4L engine in the TSX is a performance oriented engine, there is higher pressure in the combustion chamber, which could cause lower octane fuels to ignite prematurely, causing the engine to "knock." However, there may controls within the computer that could prevent this. Either way, you'll lose performance with the lower octane gas. Have you driven a TSX?
Things to consider:
1) Gas prices have dropped significantly
2) The TSX IS a luxury/compact sports car
P.S. I've test driven many cars VERY HARD. (hopefully you won't get the TSX I test drove) and If money were no object, the first two cars I would buy would be 1) BMW M3 and 2) Acura TSX
Are you more interested in the Luxury or the Sports side of the TSX?