Although I grew up knowing a lot about horse power, it was mainly of a different kind. My passion for cars was not ignited until I took part in my first Gumball Rally three years ago.

We drove from New York City to Los Angeles in 6½ days with 164 other entrants. Cruising in harmony across America’s wide open spaces were Ferraris, Lamborghinis, Porsches, Aston Martins, Morgans, Ducatis, the odd classic and even a truck. My adventurous and competitive side kicked into overdrive: this was it for me.

Another Gumball (San Francisco to Miami) and one supercar run (London to Monte Carlo) later and I was invited to appear on Top Gear’s Star in a Reasonably Priced Car feature. Just in case you aren’t a fan, each week the programme’s guest is asked to put on a helmet and race around the show’s test track at the Dunsfold aerodrome in Surrey.

Jay Kay, Jamie Oliver, Gordon Ramsay et al have given it their best. Michael Gambon almost rolled the car. The steed for these celebrity escapades? The Suzuki Liana. Reasonably priced? At £8,995, certainly. Speedy? No.

After a couple of practice laps under the guidance of a very nervous Stig, the show’s constantly helmeted — hence mysterious — racing guru, it was my turn to go solo against the clock and the virtually all-male field. Like most things in life I thought I’d give it a go. I drove the car like I’d nicked it and whipped some male motoring butt in the process.

Clarkson was gobsmacked, but I’d soundly beaten him, and even pipped Jay Kay to take the top spot. Who said women can’t drive? Amazingly, as the door of the Liana closed, many more opened. One of those doors took me to Modena for a Maserati advanced driving course, where I learnt to track-race, use skid control and all about the cars’ telemetry.

Another door took me to Goodwood for DJ Dr Fox’s Help a London Child Club Fiorano day. We raced go-karts, Caterhams, Maserati GT coupés, Ferrari 360 Modenas and my favourite, the 360 Challenge — a stripped-down, lowered racing version of the Ferrari with paddle-shift gears and roll bar. What a day that was! Yet another door has led me here, with the honour of covering Jeremy’s arse while he holidays, and the opportunity to present my literary debut. I do hope you like it.

When the idea was first put to me I thought: fantastic, I test drive anything I like. How about the Koenigsegg? “Sorry Jodie, Jeremy has just done it,” came the reply. The Enzo? I ventured. “Uhm, Jay Kay has got it covered.” The Maserati quattroporte? “No Jodie, it’s not unveiled until September.” So what can I test drive? I queried.

“The BMW Z4 2.5i convertible.”

Okay. So Jeremy has done the Koenigsegg, Damon has done the Ferrari 550 WSR and Jay has bagged the Enzo. With all respect to the Z4, I could not get the words “male” and “conspiracy” out of my head. Maybe they thought it was more of a girlie car. I’m not sure they’re right.

My first reaction when the Z4 was delivered to the photoshoot I was doing in central London last week was: thank God it’s a convertible. In a week of record British temperatures, I knew we were going to get along just fine.

Then I had a closer look and instantly liked the car’s dynamic and masculine lines. Some commentators are up in arms about the way Chris Bangle, BMW’s chief designer, has used the “flame surfacing effect” — the mixture of concave and convex surfaces on the flanks of this and BMW’s other new cars. Controversy isn’t a bad sign anyway, but I have to say I liked it.

Like the Z3 this roadster has a long bonnet, short tail and classic styling. Unlike the Z3, this model looks as if it has been working out.

When I started her up I wasn’t greeted with the roar I normally get from my 4.2 Maserati Spyder and I couldn’t help feeling a little disappointed they had given me the 2.5i and not the more powerful 3.0i version.

Being 6ft tall I normally find this type of car cramped and claustrophobic, but this wasn’t the case here. Instead it was snug but simultaneously possessed an almost spacious feel, particularly considering its size. The sports seats are set lower and further back in the wheelbase than those in the Z3, creating that extra room yet also conveying more driving excitement.

While scanning the dials for the roof control I found the dash was minimal and uncluttered. Amazingly I had the roof off and ready to go in under 10 seconds (BMW claims this to be a world record). The Porsche 911 Turbo cabriolet may tie with the latest Dodge Viper for the honour of being the fastest soft top in the world (both do 190mph), but the Porsche’s soft top takes a pitiful 20 seconds — twice as long as the Z4 — to fold down. Which are you going to do more often: drop the roof or reach 190mph? As I pulled out I can remember the great side mirror view of the Beemer’s beefy backside.

I made my way from King’s Cross, gliding through rush hour traffic, and headed for the open road. The Z4 cruised down the A3 (at just below the national speed limit) and with the sun on my back, the wind in my hair and the glowing feeling you get when you’re heading home after a long day, how could I not enjoy it.

On arrival at the test track I was looking forward to seeing how it handled. The Z4 is the first BMW to boast electric instead of hydraulic power steering, which makes it incredibly light and a reassuringly easy drive. The standard run-flat tyres therefore don’t seem too heavy.

It is good to see BMW making rear-wheel drive cars for the mass market, unlike some Japanese competitors. In my opinion driving the front wheels ruins the feel of a performance car.

The car is heavier than the Z3 — about 330lb more — but the extra power can easily make up for it. Thankfully BMW has decided against offering a 1.8 litre version, as it did with one criminally underpowered edition of the Z3. The 2.5i is the smallest Z4.

The 2.5i comes with 16in cross-spoke style alloy wheels while the 3.0i features a 17in double-spoke wheel, which is a great improvement, making the car more aggressive and better suited to its already butch styling.

Transmission is by five or six-speed manual gearbox or a five-speed automatic. The 3.0i gives you the option of a six-speed SMG clutchless manual. Then there is “dynamic drive control” which enhances throttle response and sharpens steering (only previously in the M5 and M3).

Finally the box of electronic tricks includes “dynamic traction control”, which lets the rear wheels slide out on corners, allowing a bit more back-end fun. Add it altogether and you’ve got an easy to drive but still entertaining car.

If you yearn for more electronic wizardry, optional extras include a Bluetooth mobile phone link, BMW’s answer to safe gossiping on the move, not to mention sat nav, MiniDisc and TV. Well, why not? Okay, so I’d rather have driven a £420,000 Enzo, or £354,000 Koenigsegg. But next to them the £26,655 Z4 seems reasonable. Maybe it could even give the Liana a run for its money.

VITAL STATISTICS

Model BMW Z4 2.5i
Engine type Six-cylinder, 2494cc
Power 192bhp @ 6000rpm
Torque 180 lb ft @ 3500rpm
Transmission Five-speed manual
Suspension (front) single joint spring strut axle with displaced caster; (rear) independent centrally guided axle, coil springs
Dimensions 4,091mm length; 1,781mm width; 1,299mm height
Tyres 225/50 R16
Fuel 31.7mpg (combined)
Top speed 146mph
Acceleration 0 to 62mph: 7sec
Price £26,655
Verdict It may not be an Enzo, but it's a fine summer companion, and a definite improvement on the Z3
Rating