Hurtling through the streets of Bangalore there are plenty of unexpected obstacles that can cause you to veer off course, whether a bus, a tuk tuk, a speeding moped, or even a cow.
And in the past 24 hours David Cameron has caused a couple of diversions himself.
First stop this morning was the gleaming campus of the IT business Infosys - an enormous, modern complex that looks somewhere between Disneyland and Nasa.
But after a generally well-received speech to talk up the prospects of trade between India and Britain, a question and answer session moved on to the fraught relationship between India and Pakistan.
Although in his speech Mr Cameron had tried to suggest this was not a subject on which a British prime minister should opine, he appeared to accuse Pakistan of double dealing over terrorism: "We cannot tolerate in any sense the idea that this country is allowed to look both ways and is able, in any way, to promote the export of terror whether to India, whether to Afghanistan or to anywhere else in the world."
Given the care with which he had avoided giving any judgement on this subject in his scripted speech, his comments came as rather a surprise.
And given just how fraught that particular relationship is, his intervention might not be seen by some as altogether wise.
Mr Cameron's comments came shortly after the leak of confidential "war logs" which included detailed claims that Pakistan's ISI intelligence agency was secretly helping the Taliban.
Pakistan foreign ministry spokesman Abdul Basit dismissed the claims as "crude, self-serving and unverifiable" and said Mr Cameron should not use them as a basis for his analysis of the situation, adding: "There is no question of Pakistan looking the other way."
Pakistani senator Khurshid Ahmad, vice-president of the Islamist Jamaat-e-Islami Party, warned that Mr Cameron's remarks risked fuelling "anti-American, anti-West" feeling on the streets, in an interview with BBC Radio 4's The World at One.
Along with the business secretary's now public view that the UK government's planned cap on immigration from outside the EU must be flexible, there is no doubt Mr Cameron's answer to this particularly fractious question threatens to take the shine off the £700m deal between India and BAE for Hawk trainer jets that he was pleased to announce.
But it is the second time in less than 24 hours that Mr Cameron's comments may have arched a few diplomatic eyebrows.
On Monday, in Turkey, his description of Gaza as a "prison camp" will have jangled a few Israeli nerves. One diplomatic source was clear this was further than any British minister had gone before in their assessment of the situation.
And the PM's defence that he said the same thing in the House of Commons a couple of weeks ago does not quite explain it away.
He made similar, but not identical remarks at the end of June, describing Gaza then as "effectively, a giant, open-air prison". And if nuance matters in any context, it could be argued that this is it.
In both of these cases, the countries where the remarks were made may well have been receptive audiences for Mr Cameron's message.
Turkey - previously a rare Muslim friend of Israel - is still angry with it over the raid on the flotilla to Gaza in which Turkish activists lost their lives. And India, deeply worried about rogue elements in Pakistan, may have been pleased with his forthright remarks.
But judging by the gaggle of TV satellite trucks that has been parked up, not just for the British broadcasters, at the venues where Mr Cameron has been speaking, any remarks he made were never going to be confined to the country where they were made.
And his assessment of the situation in Gaza made it back to Westminster and riled a clutch of Conservative MPs too.
Given the delicacies of both of these situations it is perhaps surprising that Mr Cameron spoke so plainly.
Especially as there had been an obvious decision not to mention certain subjects on this trip.
Having asked three different cabinet ministers in private for their views on India and Kashmir, not one of them was willing to tell me what they really thought.
They all remembered the awkward photographs and offence David Miliband, the former Foreign Secretary, caused on his previous visit to Kashmir - not to mention the slightly unedifying sight of Gordon Brown pronouncing from India on the racist row over Shilpa Shetty on Celebrity Big Brother.
Add to that the irritation in some quarters that Mr Cameron described the UK as America's "junior partner" last week, and his slip over the history of when America joined World War II and perhaps it is worth asking just what is going on?
Is this David Cameron finding his feet on the world stage, not quite yet firmly planted in the niceties of foreign affairs?
Is it the stubborn habits of opposition, when what you say to capture attention arguably matters more than what you do?
Or are these errors brought on by exhaustion from the extraordinarily intense and punishing six months of British politics that he has just been through?
Perhaps it is a little of all of the above, but maybe something else too.
David Cameron often pitches himself as a realist, a pragmatic politician more interested in solving problems than being hitched to ideology.
What you see is what you get, he often suggests, with transparency being one of his buzzwords.
The argument, honesty is the best policy, is often deployed when talking about the coming cuts.
And having witnessed a few of his Cameron Direct, or as they are now called, PM Direct, public meetings, the prime minister appears at ease with candour, and handles such question and answer sessions with ease.
He prides himself on being straight with people - refreshing, perhaps, for a Westminster politician.
But after his early foreign forays does "saying what you see" work abroad, where tangled relationships between many different countries can defy simple explanation?
Perhaps after Mr Cameron's first few overseas travels as prime minister, there is a danger that candour can be lost in translation.