Like others have commented, the OP may be located in the UK and his figure is in Pounds, which could make sense for a higher mileage V8.
In any case, as others have correctly stated, using the word "investment" in combination with a car purchase is usually a gamble. If you're intent on owning the car to enjoy it, and you have a suspicion it may also pay off down the road, so be it. But I'd certainly avoiding buying a car simply because you think it'll appreciate - or if you DO, make sure it's the equivalent of speculation funds you might also be using to buy something like a speculative stock.
Fact is, speculation does have a place in a portfolio, but most people don't tend to be disciplined about it. Let's say you have a $2M portfolio, and you're going to speculate with 5% of it - well, then spending $100k on a car you hope will appreciate down the road could suffice. But just make sure you remain disciplined that you've now MADE that speculative investment, and the remaining 95% should be invested in a more sound way.
But back to the R8. Personally, I do believe we'll see the R8 go up in value. There are a dozen reasons why I believe this... but I'm not counting on it. In fact, if it ever went up SIGNIFICANTLY in value, it would be a bit disheartening as (a) I'd probably feel bad about it driving it as much, and (b) it might force me to re-think whether I'd hold onto it indefinitely... my current plan. But my own personal forecast is that we'll likely see moderate appreciation. It's a first supercar from Audi, historically important racing heritage and pedigree, soon-to-be extinct large NA high-revving engine, etc, etc. Again, I won't go into all of the reasons for my belief, but suffice it to say there's more than a few. I wouldn't be surprised to see R8's trading at 0.8x - 1.2x original MSRP within the next decade. There's also the possibility we could see that go considerably higher depending upon other forces - such as how quickly electrification takes off, how quickly other NA engines die off, the larger world economy, etc.
As far as "investment" goes, though, I'd put a dollar into the S&P 500 any day of the week before putting a dollar into an R8 (or almost ANY other car). Even some of the most impressively appreciating cars struggled to beat the S&P 500 (and usually didn't). So, the most you can probably hope for is a situation where you get to drive a fantastic car for free... or while even seeing your car's value go up a bit. But all things considered, it'll be rare to ever wake up and say, "Wow, that car really whipped the S&P!"