Welcome back to the In-App Purchase Inspector - our regular look at free-to-play games from the consumer's perspective.

In each instalment, we consider the incentives or pressure applied to make in-app purchases, their perceived value, the expansion offered by IAPs and the overall value of the experience.

The end goal is to see whether the game makes a good enough case for us to part with our cash, or whether players are content - or engaged enough - to 'freeload'.

This time we're taking a look at Top Drives, a new vehicular collectible card game from London studio Hutch.

Vroom vroom

The success of CSR Racing and its sequel has provided ample proof that mobile games about cars don't need to be about driving, per se.

Whatever control scheme you're using, a mobile racer will always fall short of Forza. But by stripping away the actual driving and leaving only the light, rhythmic action of shifting gears, NaturalMotion allowed players to instead immerse themselves in a compelling metagame of buying and upgrading new cars.

Aiming to repeat this trick is Hutch, combining the mobile-friendly CCG formula with a racing theme. And it's off to a flyer, bagging one million downloads in its first week.

In Top Drives, each card represents a car. Attached are various stats - Top Speed, 0-60 MPH in seconds, Grip, Drive and Tyres - and all the player has to do is select which cars should participate in which races.

The key, then, is to assess the strengths of the opposition vehicle and the demands of the track. And then, after choosing your vehicle, you simply watch the race unfold.

Garage of cards

So while the formula is different to CSR Racing, and actually feels quite novel, the essential loop relies on the same race to keep your cars' stats high enough to beat ever-improving opposition.

The two currencies in Top Drives are Cash and Gold. Cash is used mainly for upgrading cards, but it can be saved up to buy card packs as well. Gold can also be used to buy card packs – exclusively so, in fact, at the premium tiers.

But while Gold is the more valuable currency, both Cash and Gold can be bought directly using real money. Cash ranges from $0.99 for 4,500 to $99.99 for 800,000, while Gold comes in bundles between $0.99 for 100 and $99.99 for 12,750.

Card packs are graded according to quality as follows: Plastic, Steel, Aluminium, Ceramic and Carbon Fiber. Higher quality packs cost more, the Carbon Fiber pack having a price tag of 1499 Gold (approximately $13), but offer rarer cars.

There are also packs that bundle together cars by era, country of origin or style.

Spoilt for choice

But while the quality of your collection may be questionable, having too few cards is rarely the problem in Top Drives.

There are chances to get free ones after very successful race, the game starts you out with a good selection of free packs, and there's enough currency flowing to invest in further packs too.

Indeed, a more likely issue you'll face is having too many cars. Every new vehicle you collect is held for 24 hours, during which time it must be either sold or added to the garage.

The catch is that the garage only has capacity for 21 cars. This is another way of monetising, with an extra five slots available for 400 Gold (approximately $4), and more available all the way up to 160 slots for 8,800 Gold (approximately $69).

It's a nice mechanic because it doesn't impinge on the non-paying user, who can simply sell unwanted cars for Cash, spend it on card packs and keep the cycle going.

Quick off the mark

What Top Drives offers is generous from the off with currency and gifts, but it uses this to its own advantage too.

Early free bundles promise tantalising rewards but don't unlock for several hours, with an intent to drive retention first and foremost. It's an approach that should yield good results for both Hutch and its players.

But surprisingly, this approach doesn't extend to its IAPs, which do not feature annuities.

For those impatient for the timed gifts, however, there's a Starter Pack which offers five cards – one Super Rare, one Rare, two Uncommon, one Common – as well as 2,200 Gold, 50,000 Cash and 10 free garage slots. At 1,100 Gold ($9.99), it's provides excellent value for money and would offer a discernible boost.

But even for the average, non-paying player, there's really very little to bang your head against in Top Drives.

Generous gifting, affordable soft currency card packs and a lack of limiting mechanics combine to make this a smooth, enjoyable journey free of roadblocks.