If the route is mainly motorways and roads with very little chance of testing out a car's cornering potential, you know that the manufacturer isn't that confident about driving qualities. If you are given a twisting mountain route, you know the company is serious about its car being good to drive.
But when a manufacturer lets you out to play on one of the finest racetracks in the world, you know it is deadly serious. So this is how I found myself in the pit lane at the Catalunya circuit, just half an hour from Barcelona, about to be let loose on the track for an unlimited number of laps in Vauxhall's new model – a VX220 with a difference. In place of the regular 2.2-litre engine, Vauxhall has crammed in a 200bhp 2.0-litre turbocharged engine from the Astra Coupe.
With a kerb weight of just 930kg, the pretty VX220 Turbo, which is due for its international debut at this week's Geneva Motor Show, offers astonishing performance which puts it into the supercar league – 0-62mph acceleration in 4.7 seconds and a top speed of 151mph.
And after a couple of familiarisation laps around the circuit following a professional racing driver, all that performance was mine to explore. The figures may be daunting, but the chassis (refined by Lotus) lets you explore it to the full.
In fact it's a bit of a hero car because it lets you feel as though you are a racing driver. The short-throw gearbox has that wonderful metallic, mechanical feel and it works so well that keeping the turbocharged engine on the boil is no problem at all.
By the end of Catalunya's main straight I was in fifth gear and travelling at roughly 130mph but a long, tight corner was approaching fast. Slam on the brakes and the speed is wiped off effortlessly.
Once the car is settled it's time for the fun – cornering. But the first few times you pitch the car into a corner you metaphorically kick yourself because it is evident you could have gone into that corner much, much faster.
However, after a few laps my confidence was sky-high and I felt like a proper racing driver – blipping the throttle on downshifts, clipping apexes, accelerating hard and generally having great fun.
The VX is so well balanced that track work is a joy – but with 200bhp in a featherweight car, you can get the back end sliding about before gathering it all together and carrying on with the rest of the lap.
After countless laps, and confident I must have set the lap record at the track, I returned to the pits and then headed off into Barcelona city centre in the rush hour. It may not be the ideal car for stop-start driving, but the VX performed well enough, even though it felt limited by being in the confines of a city.
Luckily the following day saw me trying out the VX in its second home (after the racetrack) – a 120-mile route on switchback mountain roads high in the hills above Barcelona. Once again I felt part of the car but after 50 or so miles my back was aching and I was getting frustrated at not being able to fully unleash the VX's 200bhp. As everyday transport, the VX probably won't even come into your mind, and I can't say I blame you. But if your drivers don't cover many miles and only have a short journey into the office each day, I can guarantee you they will arrive at work with a huge smile.
For the money (£25,495 on-the-road), you can't get anywhere near the VX for performance. And as a token gesture to fleet, it only emits 202g/km of CO2 – putting it in the 24% band for benefit-in-kind tax for 2003/04.
What a result.
Model: Vauxhall VX220 Turbo
Price (OTR): £25,495
Engine (cc): 1,998
Max power (bhp/rpm): 200/5,500
Max torque (lb-ft/rpm): 184/1,950
Max speed (mph): 151
0-62mph (secs): 4.7
Fuel consumption (mpg): 33.3
CO2 emissions (g/km): 202
CAP residual value: (3yrs/60,000 miles): £7,750/31%