Vijay Pattni looks at used sportscar bargains on Auto Trader to help you save more than £20,009 in 2009.

Making a sportscar is a numbers game – start with a small, rear-wheel-drive layout, minus the practicality, add a monster engine…and multiply the fun.

And the result is an exhilarating drive – but now this sportscar-numbers-game comes back with an even bigger result, thanks to used car prices.

We’ve rounded up some top bargains on fantastic drop-top sportscars, including a 300bhp Porker…

BMW Z4

BMW stunned Paris Motor Show audiences in 2002 when it unveiled its all new roadster – the BMW Z4.

Taking over from the hugely successful BMW Z3, the new Z4 marked out a different kind of sportscar. With achingly good looks and sharp handling, the Z4 instantly marked itself out as a proper driver’s car, and still looks sharp, thanks to controversial designer Chris Bangle’s unique ‘flame surfacing’.

And who can dispute BMW’s range of sensational petrol engines? Opt for the 2.5-litre or above and you’ll get a sonorous straight-six powerplant with Munich muscle.

We found this 2008 BMW Z4 3.0si with a paltry 2,000 miles on the clock for just £24,995 – making a huge saving of £9,305.

Read our review of the BMW Z4

Porsche Boxster

“Porsche design…the least a man can get.”

Clarkson doesn’t think Porsche makes an effort when restyling its cars – but if it looks good…don’t change it.

And with a sharpened front end and a host of tuning tweaks, the new generation Porsche Boxster is the finest handling sportscar.

The top-of-the-range ‘S’ model packs a 300bhp 3.4-litre ‘boxer’ style engine, and can accelerate from 0-62mph in just 5.4 seconds, before hitting a top speed of 169mph.

We found a ‘Porsche Approved’ 2008 Porsche Boxster S with 6,500 miles on the clock for £31,950, saving £7,194 from its list price.

Read our review of the Porsche Boxster S

Mercedes-Benz SLK

Forget the boulevard cruiser that was the original SLK – Mercedes-Benz has stepped up the ante with its second generation SLK roadster.

The new beefed-up SLK boasts an F1-inspired nose and stylish touches along the body, to complement a great range of petrol engines – including a 231bhp 3-litre V6 which accelerates from 0-62mph in 6.3 seconds – and sharp handling.

We found this 2008 Mercedes-Benz SLK 280 – with a cracking set of alloy wheels and 10,500 miles on the clock – for £25,995, saving £5,031 off the list price.

Read our review of the Mercedes Benz SLK 280

Honda S2000

Who said Granddads can’t dance?

In the company of its German rivals, the Honda S2000 looks a little…dated. But while it may have been around for 10 years, the little Honda still looks cool – if the interior lets it down somewhat – and exudes the classic sportscar appeal.

Jump inside the snug-fit cockpit, press the red starter button and marvel in the S2000’s magnificent handling attributes – its agile, quick and smooth over all surfaces, while the 237bhp engine means acceleration is rapid, if strained.

We found this 2008 Honda S2000 ‘GT’ with 5,241 miles on the clock for £18,500 – making a massive saving of £10,170.

Read our review of the Honda S2000 GT

Audi TT

Style over substance isn’t always a bad thing – who really wants to go at breakneck speeds in something that looks like a lawnmower?

Audi prescribed to this notion before with its original TT, marking it out as a design icon. The drive was ok, but in the company of rivals it wasn’t the best.

Now however, the balance has been redressed – as has the new TT. With muscular looks and an engaging drive, the new TT is an astonishing sportscar. We drove the new TT and found that Audi “has turned the TT into a genuine driving enthusiasts’ car, with poise and agility at any speed.”

A 3.2-litre TT with the semi-automatic ‘S-Tronic’ gearshift costs £30,055 brand new, but we found a 2008 Audi TT 3.2-litre V6 Quattro with S-Tronic and 5,200 miles on the clock for £25,850.

Read our review of the Audi TT

Are you buying a new or used car?

Watch the new Audi TT in action: