No prizes for guessing what’s going to be the least relevant, most exciting twin test of 2009. If it’s not the Aston One-77 versus the gloriously bonkers Merc SLR Stirling Moss I’ll eat my laptop.

Merc6 The Merc look likes being rather cheaper, probably £900,000 once local taxes have been added to its 750,000 Euro list price compared to around £1.2 million, but the Aston is more powerful (700bhp vs 650bhp) and seems likely to come with a transmission somewhat more noble than the five speed slushmatic gearbox used by all SLRs.

But from the shots we’ve seen so far it’s the Merc that’s the maddest looking and at only a little over 1500kg, it’s more than 200kg lighter than a standard SLR. Then again, the Aston’s 7-litre V12 engine is going to be a close relative of that used by the DBR9 race car and having been lucky enough to sample that, it’s hard to see how Merc’s supercharged V8 is going to hold a candle to it.

But the real challenge is going to be getting the two together on the same stretch of tarmac.

Mercedes says all 75 Stirling Mosses have already been sold to loyal customers and while there is much rumour and speculation about the order bank for the One-77, there is no confirmed news and given that just 77 will be built anyway, it’s fair to say they’re not exactly going to be littering the press fleet.

See more pics of the Mercedes SLR Stirling Moss

01_aston_one_splash Stirling’s view of the two would be instructive. He is well remembered for his record-breaking Mille Miglia drive in the original SLR in 1955 but less easy to recall these days is the fact that half a century ago, he played the single most important role in snatching the 1959 World Sportscar Championship for Aston Martin, by far the most important title in the company’s racing history before or since.

In his 80th year, Stirling is still racing and still competitive, winning his class at Spa this October. I just hope he doesn’t have a contract with Mercedes that would preclude his involvement: his opinions, always ripe, honest and refreshingly off-message, would be worth hearing.